Jeff - I have some information attributed to John Thorp (but I can't point you to the source). He indicated that the total inlet size in sq inches should be the hp *.35. The exit air needs to be 2.5 times the exit air. I too had some oil cooling problems on my c-85 and found the exit air plays just as much in the cooling as the inlet air. In fact my exit outlet ended up being @ 2.85 times larger and I still see 200-210 degrees in mid-summer ( it does come down to 190-195 in cruise flight). I also played with a lip and it didn't help so I removed it. Hope this helps some.
Rick Human N202RH Houston, Tx
