HolyCow98,
I think that you should still get a fairly accurate rating translation with the look-up table generated from the league that you described. Feel free to go ahead and use that.
However, you should use the updated Rating Translator v0.81b. In v0.81b, I have fixed a small coding error regrading to H/9, K/9, BB/9, HR/9 ,and WHIP calculation. Now v0.81b should give you more accurate results for expected pitching performance.