190xt advise needed

I have a 65 190xt gas and I love it for a daily chore tractor. It only runs about 15 min a day in the winter. I have rebuilt both the PD and transmission. The problem I am having now is a major oil leak at the front main seal. I have no idea if it is caused by bad main bearings. The motor sounds to me like it has wristpin noise, and it only carries about 27psi oil pressure when warm at high rpm. But it runs ok.  The easier and cheaper fix is to put a diesel in it, as production numbers were low on the gassers and parts weren't picked up by aftermarket. Anyone have a idea what a OH costs on a gas 190xt? Any thoughts are apprieciated.

Make sure it's not the timing/front adaptor plate that has come loose.  It is something that can happen on 301s.  I really doubt that main bearings being bad would cause enough play in the crank for the front main seal to go out, as you would more than likely break a crank from that kind of play.  If it has poor oil pressure, that would be your main or rod bearings or a weak oil pump/bad relief valve/spring (I want to think the cam bearings are not pressure lubed on a 301, but I could be wrong on the front 2, the rear bearing I know is lubed by "magic" as one person told me, basically splash lubed).  If I were you, I would run a compression test and see how your numbers compare to factory specs.  If it looks good, I would consider doing an under-haul (new bearings) and checking the wrist pins for excessive play while you have the pan off and the rods loose.  The bearings should be the same as the diesel.  Also, check to make sure your timing is set correct, to rule out pre-ignition as your source of the knocking noise.

Hurst