Tractor Repair: International B-414 gas in base, engine oil pressure, international harvestor

Question
I have a 1963 International Harvestor B414 gas tractor. I've rebuilt a engine with 30 hours on the new motor. I'm haveing trouble with gas getting into the base of the engine & oil pressure going down to nothing. I've checked the float on the carb & it seems fine. I've also rebuilt the fuel (lift) pump & encountered the same problem. I have a new pump on order. Is there any other thing I'm over looking that may cause this problem ?
Thanks for your help
Brad

Answer
Hello,

  The lift pump and the carburetor are the only two things that could cause it, so you are not overlooking anything but you need to go a step farther with the carburetor.  Even though the  float may seem fine, the needle valve and seat should be replaced and make sure the fuel supply is clean.

                      Arnie