What??? Please don’t!!!
You just said you’ve never been a fan of V6s or V8s but Dennis has an I6 laying around. Now a Chevy V8?? Putting a big Chevy Motor in a small Nissan??? Please don’t. The S12 is already rare enough to have this happen to it.
The V8 will throw off the balance of that car signficantly.
A 4cyl is what that car needs. CA is lighter than the SR
Even if you must a Rotary is a better option by far.