I think you'll find that the S13 SR20 and S13 CA18 crossmembers are the same. So using this information, if you use engine and engine mounts that come with either engine, that it will sit on the same crossmember. But the SR20 won't fit in some 1200 installs because of brake/clutch master cylinder clearances.
Also the SR20 gearbox bellhousing is ~1 inch larger in diameter, so you'd need to modify the 1200 tunnel to make it fit.