Right, lets go for some truth

Theres big differences (not jus looks) between S13 n S14 chassis too, but as you just seem interested in the engines, lets go there.

All UK spec and early Jap spec S13s had CA18DETs, 1.8 16v turbos, 170bhp, good for 250odd on standard turbo etc with a better cooler, 280odd on standard inj, 330odd on standard internals without any real probs, sometimes more if want, but not that common.
Jap spec ones had a different, less efficient head, but jap CA18s are pretty rare anyhow, as 90% of S13 180s and Silvias that have been imported are SR20 engined.

Late jap spec S13s, S14s, S14a, and S15s, came with various variations (mainly that S14/S15 had VVT, and inlet manifolds etc changed, but nothing much, id go for an early red top if was me) of the SR20DET, 2litre 16v turbos.
Good for 280odd on standard bits n a decent cooler, bigger bolt on stuff and can go for plenty more, 400+ has been done on standard bottomend good number of times.

CA18s have a kinda undeserved rep for doing big ends. They no worse at them than any other car of similar revs and bhp per litre.
Its just most of them have done a lot of miles and many not treated to well.
Ones that have had em replaced often has that done badly too.
Only dont see it on Cossies as they usually get rebuilt for some other reason long before they hit the miles where the big ends start to die!
My one lasted 99,000 miles before they went, and it was FAR from a pampered car, infact it was a cheap abused shed

SR20s big ends go too, and you see some like it now as they also often getting to 90k+ and led hard lives.
Ive seen ones last 130k with ease and abused to fuck though, so they do well when they want.
SR20s NEVER snap cams, ever, not unless they installed wrong, like any other car.
What they DO do is somtimes snap rocker arms, esp bouncing off the limiter for long times on modded cars.

To swap engines youd need all the bits, inc loom, manifolds, etc, jus like 90% of cars.
CAs and SRs arnt related at all, stuff like aftermarket intercoolers, turbos, exhausts, etc can be shared, but are all different as standard.

Mounts are one either side of the block, bolted on, which join to the chassis rails either side of the engine bay.

SR20 swap into a S13 is piss as late ones came with them, but ideally need a S13 SR20 box as it a bit smaller IIRC.
SR20 engine is a bit bigger in dimensions, but not by much.

Skyline RB20/25/26/30 engines fit in S13/14/15s without much grief too.

Tell me what you got in mind and i can prob help more.