I have an automatic b20z in my 92. All that’s different that i can remember is the flywheel. Just use your old one along with the obvious stuff that you need to transfer over and it would be fine.
I am wondering though if there’s a difference between the auto and manual cams.
They made standard CR-V’s, they are just rare. the auto B20 has a Flexplate, not a flywheel. The cams should be identical because the motor was tuned from the factory to produce excellent low-end, something the auto model would need.
make sure you use the flywheel bolts off your b18, NOT the bolts from the b20. the b20 will say AT on the bolts and the b18 flywheel bolts will say MT. the AT bolts are shorter than the MT b/c the flywheel is thicker than the plate from the auto tranny