9 bolt posi, damn that must be really rare... but if your car is revving up and idling rough, it could be timing, needs a tune up, bad gas, gas filter, or even a messed up carb (my truck floods out at times, 'cause the carb is fucked) but when buyin' a car, look for any and everything that is wrong with it, and beware of a car that's "too good to be true" a motor should have some dirt on it, but not a hell of a lot, and make sure to check the oil and water levels, you can tell a lot about how the car was cared for by the levels of the fluids, also if you smell the oil and it smells burnt it could be a sign of how worn the inside of the motor is, after I spun a main berring it smelt really strong of a burning smell, also if water is in the oil it means there's a head gasket or head problem... but rebuilt should be done professionally, ask for reciepts and check to see that they machined things... and ask why it was rebuilt... but good luck (not sure if I really helped any)