Something is wrong somewhere. You say is has 220-240 PSI, yet the engine wants timing like it's a 7.5:1 motor. I'd be rechecking some things. There's no way in the world it will want that much timing with such great cylinder pressure. You sure it wasn't 120-140?
I think it's compression is much higher especially if it's wanting that much initial timing. And who would put together a motor with that cam with low compression...