So, I'll start off by saying that I really like this team. You've got a lot of offensive firepower, a strong goalie who is used to playing behind fairly wide-open offensive teams, and good roster-coach synergy. Should be one of the real contenders to win it all.
1st line: I thought waiting on Sittler like you did was brilliant. With Howe leading the way, you could afford to wait at that position, and I think you waited just long enough, and got excellent value. Wouldn't want a guy lower than Sittler as a 1st liner, but he's fine there. Tons of offensive firepower, plenty of grit, and enough defense to hold up (though I think Malone's defensive value is limited on the wing). Should be a lethal unit.
2nd line: Another quite strong unit, following a theme of scoring prowess all over the lineup. You've got a sort of puckwinning-by-committee setup here which I think will work with none of the three being dominant physically, but each being able to contribute. Richard's excellent two-way ability is enough for the line to be defensively cohesive, and offensively, they are excellent, with Richard among the best ES centers in history, and good wingers. Another excellent line.
3rd line: A little less enamored with this unit. Colville basically has Richard's role as the defensive conscience of the unit, and that's fine...I'm just not in love with Mogilny at even strength. Very talented, but his offensive contributions were so uneven. Enough grit between Marchand and Colville. Nothing terribly wrong with the unit...I'm just not much a fan of AlMo.
4th line: Mainly a special teams unit, and good in that role. Don't see them giving you much at even strength (Robert brings down an otherwise promising unit), but that's not terribly important.
1st pairing: I think Stevens is a below-average #1D at 24 teams, and in spite of past draft position, Larry Murphy is at the bottom-end of legit #2s, in my opinion (I've got him in the 49-52 range all-time). It's a good fit in terms of style, but not a great unit in terms of talent.
2nd pairing: Art Coulter is an excellent #3, imo. I've got him in the same tier as Larry Murphy. Pratt on a 2nd pairing (and where you drafted him) is probably my least favorite part of your team. I think he's an elite #5 or a low-end #4 at 24 teams (I have him as around the 100th best D of all-time) He's a guy whose best seasons came during the war years, and I don't think he was particularly sound defensively. Obviously, he's paired with a strong defensive #3 here, so that helps, but I think you could have done better, and he brings the unit down somewhat. Overall, a slightly above-average pairing, mainly because of Coulter.
3rd pairing: You surprised me with Pietrangelo, but I like the pick. I think both he and Harmon are solid #5s at 24 teams, and overall make for a strong third pairing, which is increasingly important as scoring third lines have become the norm in the draft.
Goaltending: Tretiak is a good goalie in a draft of this size, and a guy who did well dealing with a lot of shots, which I expect he will face behind a somewhat below-average defense (mainly due to the 1st pairing).
Coaching: Strong coach-roster synergy here. Sather is in the discussion for being in the top-10 coaches of all-time, and you've given him the keys to a team that should execute his tactics very well.
Power play: Not sure how I feel about Gordie Howe at the point, and Pratt is only ok as a second pointman on a 1st unit at this level. Obviously, Howe is amazing, but I just don't know that this is the best use of his talents. The forwards are ok. Malone is very good, but the other two look fairly mediocre as 1st unit guys. Malone has more grit than he is generally given credit for and Sittler was a scrapper, so they should be fine cycling the puck along the boards, but the talent is kinda meh. Second unit is pretty good, with good players at every position. Not in love with using Henri Richard on a PP, but I understand that he is too good not to use in that capacity, and I think he'll be fine in that role, though it does take away from his ES production somewhat (I gather Toe Blake liked to send Richard's line out after penalties to either team).
Penalty kill: Not sure how I feel about the three forwards look. I understand that Frank Boucher had a lot of success with this as a coach, but I'm not certain that this would translate well to the modern game. Outside of Crawford, the personnel are quite strong, and Tretiak is good, but I don't know enough about Crawford to judge him as a penalty-killer. I gather that Crawford was a good back-checker, but he spent almost the entirety of his career before there even were powerplays in the eastern leagues. Seems like a potential weakness. Second unit looks allright. Is Marchand really that great of a PKer? I honestly don't know, but I bet you do. The rest of the skaters are good, and Fleury is underrated as a penalty-killer, imo.
Overall, an excellent team, and one that has a real chance at the Cup. How well the defense and penalty kill units hold up will likely determine how far you advance.