There are too many things to take into consideration before a correlation can be established: linemates, ice time (even strength and powerplay), playing style...If it is for fantasy hockey purposes, I would say that a guy has to be amongst the best in his league before he reaches the age of 21 yrs old. Here's a crapshoot at how I think it could translate in terms of PPG RSL: 100% SWE: 80% CZE: 70% FIN: 60% AHL: 60% SVK: 50% DEL: 50%
http://hockeyanalytics.com/Research_files/League_Equivalencies.pdf This document seems pretty reasonable.