What is the chamber volume size on the late 70's 330 BBC heads?

118cc for the peanut port heads. Take the head number and do a google search for sure.

most heads after 72 are 119. at least RATED 119. get a Walmart 4 buck flavor shooter in the cooking section. 30cc syringe. accurate enough. piece of plexi about 6 inches square. drill a hole about 3/8ths on one side. grease plexi and stick it to the head. start shooting water in to the hole. with valves and spark plug, obviously. 25cc at a time. now you know the chamber volume. the heads from an 02 461 hp 502 are 113.5cc. they look just like the 119 cc peanut head chambers I have.

is that 461 hp 502 a gm crate engine?

Yes. Bought it with cracked block. Got frozen.

my 781s both measured at 118 for what its worth

Most likely 118 as others have said