gas fuel oil crankcase

Newbie here... Model M301 EZGO 10+ years old. Used daily for short distances re: ranch chores (no prolonged usage). Every 2-3 months fails to start. Battery, alternator output, air filter, fuel filter/line, fuel pump all check OK. Did complete carburetor service (cleaned and re-assembled)...

Hey guys, I've retrofitted an FE400 (FE400D-ES05) into my 1996 Carryall II and have since been finding gas in my crankcase when checking the oil. After about 30 hours, the dipstick smells like gas and is about 1/2" over the full mark. The oil is obviously too thin as well - quickly dripping off...