Which heads?

[POPS6T6]

I bought a new motor (casting # 4179930-360) for my car, and it came with the J heads installed on it (I haven't pulled them yet so haven't been able to get casting numbers) but they do have the J stamped on them.. I also have a set of heads with a casting # of 4027596 which I hear are pretty good heads. Without knowing the casting # of the J heads, what would the general consensus be on which heads I should rebuild?

As always, thanks for any advice!

 

[rumblefish360]

The J's are a 915 casting. Either head will do. The J's may very well have the 1.88 intake valve which is not an issue for street performance. They flow almost exactly the same cfm.