85 turbocharged jetta won't run

i just finished turboing an 8v and put a gti motor into my jetta it leaks oil i've changed as many gaskets as i could find but now my oil pressure light keeps going on and i know i have enough oil i compensated for the turbo i've figured out its one of my sensors...hopefully. i know theres 2 which is for low pressure and which is for high pressure.also what are some reasons why im not getting enough pressure to the top of my motor.