A few years ago, Tom Langdon, before he retired from GM, was kind enough to provide me some combustion chamber cc's based on casting numbers:
3836848 79.1 cc's
3835913 86.2 cc's
3836850 86.2 cc's
3703570 95.5 cc's
I think i missed what you intend to use this motor for, but the cam specs look like a street motor. If your head is severely milled and milled incorrectly, give up on this head, particularly if this is a street motor. 1/8 cuts were common years ago, some milled more but 1/8 was more common. You had to play with those heads to get the geometry right. I did one and the performance gain was not worth the effort ( I was racing a 235). By the way, few of the block deck heights ever come up to spec and there is a good bit of material that can be removed from the deck. Big cuts end up with the same issues with geometry. Frankly, you will be much happier with an accurately machined head. The 848's are not that hard to come by and the aggravation of trying to save that head, shimming, custom push rods, etc., is not worth it in my humble opinion. As for the compressed volume for a 261 head gasket, a felpro engineer gave me the spec for their gasket (i was younger then and did not write the actual part number down, duh)so whatever part number they had in the early 90's was 10.82 cc's. Good building to you!
