I'm in the process of building a D15z1 engine for my 93' hatch, I've gotten all the goodies including the trans. Wish I could use the hf trans from my sons 90' civic, but I'm told it will not work due to the rear mount and VSS tho the mount look the same. Anyways, the ecu I got is a California ecu P07-L00. Will this still work with my setup I'm in Tx, will I enconter a problem during inspection time. I know I have to use the 4 wire o2 but will there be anything else?
The L00 will work and you shouldn't have any problem during inspection. I don't know what the TX inspectors are like, but the ones here in CO didn't even recognize that I had a vtec engine in a 90 civic. Beef is correct, you won't have lean burn or the shift indicator light. Otherwise the ecus are the same. Your gas mileage will suffer a little though.
The only problem I know you'd have with the transmission is that the 90 uses a cable clutch and the 93 is hydraulic. I don't know about the other questions.