I will do some number crunching on the 285 and see what compression turns out to be. Be a guessing game till I figger out whether I do the 302 heads or not.
FWIW, I ran numbers on the 526's vs 285's with your heads unmilled and a .028" thick head gasket and got 8.9 vs 7.8 Static CR. So the 285's drop over a point in CR..... and Dynamic CR with the 285's will be waaaay down with a 270 cam.