Any open motor has the tendancy to blow out oil because of RPM range. Dover vents his Sa's out the top of the block where the gov shaft would be and also runs a PCV valve in the line. Also your catch can has to breathe more out than in or it will not work correctly so make sure you have bigger outlets than inlets they also may need to be baffled to trap the oil in the canister. I would run 2 3/8 breathers off the motor to the canister and 2 1/2" hoses out the top of the canister.