yeah, you have to do an OBD1 to OBD0 conversion. i dont know if anyone makes mounts for that gen integra, but i have heard that its a VERY tight squeeze getting a B18 in there.
if you want to go B18 i would recommend trying to procure a 90-91 integra B18. so you dont have to do the OBD conversion.
my personal recommendation for a 1g integra is a B16. its smaller and fits easier, but you do still have to do the OBD conversion.