True or false when swapping a B20B into a 1991 Integra GS:
You can retain your stock a/c system with a B20
You do not need to buy a thinner a/c fan
You can still use your existing cruise control system with a B20
You can use your existing ECU if you use the B18 dizzy, injectors and wiring harness
Any B-series header/exhaust manifold or intake manifold will bolt to a B20
1)True
2)True
3)True
4)True
5)True… Using a 97 Ls IM and 91 EM(for now)
5 Is only half true. Any b series header will bolt to the b20 head, but not all b series intake manifolds will fit. Any b series non vtec intake manifold will bolt up, b18c1 will not fit, b18c5/b16/b17 will fit with modification.
I guess my main concern was retaining my ac. I want to go non-vtec b20 so I can basically have a stock-ish, reliable engine with low low miles. (my B18A is at almost 200k miles) That is kickass!
Mounting is the same for the compressor, though? I realize that i have to transfer over my crankshaft pulley to the B20, so it wont rub or screw anything up. But will that affect the space between the ac fan and the compressor? I’ve read in some posts that the block of the b20 and b18 are very similar in outer dimensions, its only the inner measurements that differ. If this is indeed true, then there wouldnt be an issue.
Either way, thank you both for the information! 
B20 here i come…
ok… so this ac this was also half truth… There are people who were able to retain their AC… I was not.
JDM B20B, P8R head… Ac fan didn’t fit because of clearance issues with the echaust manifold (from a B18a).
Civic Si Radiator made clearance better but was going to have to trim the housing to fit it in.
I did a 96 jdm B20 w/ P8R head also… everything worked fine. I transfered the a/c and p/s brackets from the b18a and I used the b20 alternator bracket.
still not 100 %… yes it will more than likely be the case that it will fit, but I am proof that it isn’t certain.