Well, I've developed a bit of a theory.
1st generation parelled 4th generation. Here's some evidence.
1) In R/B/Y you skipped the viridian gym, it was locked. In R/S/E, you skipped the petalburg gym, your dad wouldn't let you yet. You later came back to both these "first" gyms and had the battles.
2) The Elite Four levels were on the same scale.
3) The third gyms were both electric, the firsts were both rock
4) There were islands with a gym on them in the southwest corner of both maps. (The one in Johto doesn't count, as that was a peninsula in the northwest of Hoenn if my understanding of the pokemon world map is correct.
This is why I've come to think that perhaps the 2nd and 4th generations will parellel eachother like this, however this is only a theory. I have some reasons for this as well.
1) Diaruga and Parukia, as two major legendaries, seem to parrellel Lugia and Ho-oh as another pair of major legendaries.
2) 2nd generation consisted of many evolutions and pre-evolutions of pokemon, and based on the pokemon already revealed, 4th generation seems to follow the same trend.
So I'm going to say 40-50 for the elite four, as that was how it was in G/S/C, however this is just a THEORY.