I have a pair of heads that came with a 396 I purchased and I am sure one was changed for some reason.
The casting #'s are 3917215 and 3931063 dated I-6-7 and J-15 -8 respectively.
I am hoping they are compatible in the flow # area more than anything else.
Any head gurus out there that can shed light on this for me?
Any info much appreciated!
thanks all.

Believe it or not I'm pretty sure this question has been asked on here before. Try typing 215 and 063 into the search function. Those heads are very similar in design, combustion chambers and ports are nearly the same. Flow # should be compatible.

Yep, close enough to be the same.

I have yet to CC the chambers, are they the same also?
Thanks.

Yep, close enough to be the same.

yup..they will cc close...you are good to go.

Thanks all! Sounds great.