I have a 1997 integra shell with an auto trans and I’m trying to swap in a b18a1 out of a 1990 integra obd 0, I have the obd 2 wiring harness and ecu from the 97 shell. Im not worried about emissions just want to know what would be the easiest way to get everything in and running. I also have the auto trans from the 90 shell.

 

"I think" wouldn't it be better to get the complete DA engine wire harness, its ecu and and use it. Probably other ways to go about it but your in for a bit of work.
I've never done it before but that's what I would look into doing just so its all plug and play except the wiring in and adapting it to the chassis.