B Schein

I am going to start working on wiring on my car very soon. What I have is a 67 camaro that I put a 98 dash in as well as ls1/t56. I didnt buy a wrecked car so I have been collecting it piece buy piece. What I currently have is the cross car, main body harness, BCM, steering column, tail light harness, and under hood harness this is all from a 98 Trans am. I have a pedal assembly form a 95 six cylinder car that had I five speed I bought it for the switches I will be using after market pedal assembly hopefully they are the same plugs as an ls1 car but I haven’t verified it yet. So here is my first question I have a 99 engine harness and ECU. I know that 98 had different pinouts on the ECU compared to 99 and up but will all the plugs that go from the engine to body harness be the same pinouts or did they change also, and does any one see any problem with doing it this way. I want to use the wiring from the 4th gen so I can get all the systems on the car to work like keyless entry, vats, power windows, power door locks, alarm, trunk release and all that type of stuff but manly I am doing this to use the factory gage cluster which leads me to my second question. I got a 150 mph cluster of ebay for $3.50 the guy spelled it wrong. He didn’t know what year car it came from. Are these clusters different form year to year or should any of them work with my 98 wiring and also is there any way I can get the odometer set back to zero so when I go to register my car I dont have to say it has however many miles the odometer already say it has.