Just to add to the conversation,
I've just changed my 95 manifold to a 97 manifold, added phenolic spacers and gone to top feed 850 sards with a parallel fuel setup..

Couple of notes to consider.
Have a look at some RS Forums, or google rs ......, not just wrx, as everything your looking at has been done before more than likely with the RS (as good as exactly the same as early wrx)

Need to change Throttle position sensor adapter (94-96 is 4 wire, later is 3 wires)
If keeping Idle control valve, you need to re-route the hose to your inlet, easy enough to do..
Need to change or adapt accelerator cable as its on the other side of throttle body.
Top feed conversion was pretty straight forward and easy enough to do.
I've had to make some adaptions to the header tank, as the top feeds slightly foul where it normally would mount to manifold.
I went to vf34 so Advantage of going to 97+ manifold is you can go with direct entry turbo and inlet..

Should be firing it up in the next 2-3 weeks hopefully once the vipec goes in, but all looks ok to me..
Hope is of some help in your thinking..
Cheers