The compression will be slightly higher but that's not the issue. Too much initial timing is, as you confirmed earlier. Have you ever confirmed TDC? Initial timing? Total timing?
I had the same issue with my 400. Too much initial to start easily when warm, but didn't want to back off the timing because it ran well. I ended up recurving my distributor to allow the engine to start and run (cured my idle surge as well) and retain the proper timing when fully advanced.
