Cadillac CTS-V - LS swaps

We'll I am in the process of doing LS3 uppers but I might have run into a problem. Ive priced everything I need and all the parts to go with it too

LS3 L92 heads
LS3 intake (fast intake later on)
I cant remember if my installer told me fuel injector spacers; or fuel rail spacers. But either way I need spacers for one of them
New Head gaskets

One problem that I want to solve before buying the heads; and may be the dealbreaker for me here is if my headers dont fit LS3 heads. I know they arent D port, but ive heard they sit a little higher than LS2 heads

Anyone know?

One problem that I want to solve before buying the heads; and may be the deal breaker for me here is if my headers don't fit LS3 heads. I know they aren't D port, but I've heard they sit a little higher than LS2 heads.

Anyone know?

You're good to go, they'll fit just fine.

Personal experience?

I assume your have an LS2?

Yesssir