SC vs 964 Throttle Bodies
 

I am converting my SC to EFI, and using a 964 intake plenum. My original plan was to use the slightly smaller SC TB however, so I made an adapter out of thick phenolic to smooth the transition. However that adapter has caused another issue is that it causes the stock 964 AF housing not to mate up with the mounting tabs on the intake spider.

Would there be any problem (other than probably making it sensitive to coming off idle) using the regular 964 TB. Engine is otherwise stock.

I don't know how big the throttle plate is for a 964 throttle body, but I am using a Mustang 70mm throttle body on my 3.0 liter turbo EFI conversion with a Carrera 3.2 intake manifold, and I have no issues with throttle response or regulating the throttle. So you should be fine.
If you were using individual throttle bodies, you would have even more throttle area, but those setup's seen to work fine when properly tuned and the response is amazing.

Thanks for your input. I was worried there could be some issues coming off idle.

Side effects include better throttle response