Bill
One thing you might want to do is put a check valve in the vent line so if the car ever get inverted for any reason...it won't run out... then get a filter like they use on a Harley..... to vent the
oil system .......and put on the end of the hose...or run the hose out the back of the car.... normal procedure in racing...
Also the fuel gauge sending units that I have played with are very touchy.... and one potentiometer is for full and the other is for empty.... if you barely move the pot.... the gauge move a lot...
Morris