If you are putting this B16A into a 90-91 Integra, it is pretty easy, no need to reshape the bay or even get a motor mount kit. Just add wires for VTEC and go. If you are trying to put it into a 92-93 you are installing an engine older than the chassis into it which will be both illegal and difficult to wire.
Before you do, consider this: The B16 came in the DA for 2 or 3 years. Then they dumped it for the B18C. I think even Honda realized that the B16 doesn't produce enough torque for that chassis. It does work and you will have a reasonably fast car, but people with a comprably built B17, B18C, or LSVTEC will walk all over it. Just make sure you know what you are getting before you purchase the swap.