NON- recomended swaps:
b16 SiR/ B18A/ ZC/ d16a6/d16a8/d16a9/b20a/b21a//b18c1/b18c5/b18b1/h22a/f20/f22a/all C-series into a 2001+ civic/rsx
b16 SiR/EW4/B18A/ ZC/ d16a6/d16a8/d16a9/b20a/b21a/all k-series/ all c-series/ into 92-00 Civic
b16a2/ b16a3/ b16a SiR II/b20b/b20z/b21a/b20a/b18c1/b18c5/b18b1/h22a/f20/f22a/ all C-series/all K-series/ into 91 or older civic
preludes/accords, stick to the F and H series.
Anything can fit in any car with a hacksaw and all kinds of money... but to keep it simple, try your best to stick to the above. It will save you wiring problems and will most likely be cheaper than trying to, for example, stick a b16a SiR1 into an EG chassis vs. just buying the SiR2 in the first place.
I'm sure i missed a...