I'd use a 23 escape manifold, a mild set of cams. A taller deck height, like you said means spacers, maybe you could use a 23 mount w/ shorter spacers. Figure out if a 23 escape pcm would work= The 23 escape is the only 23 w/o imrc, but uses the imtv, which would be great to use. Using a 20 manifold on 25 You might not have an issue w/ the grunt, but I'd remove the imrc= tumble flaps. The 20 has only length of runners, wheres the 23 uses two lengths of runners= imtv. A pcm swap you'd need. I'd add a 2.5'' flex back system for sure. Have you checked out a 25 Mazda 3?
Introduce Mr. Torsen to the mix
Bigger brakes then you- D23 crew- D-Tech- Sedan Revolution= #131