89 s10 v8 conversion

I have installed a 350 4 barrel into a 89 s10. I am having problems with the wiring harness as I have converted a 93 350 into a carb. unit and installed a 86 s10 wiring harness into the 89. I cannot get the wipers to work and the High Low beam switch is backwards. Also the fuel tank guage is showing 3/4 when the tank is full.