I think I would stay with the 302 since everything is already setup. A nice 331 stroker will give lots of power if built properly. I would stay away from the 347, lots of problems with longevity. We just built a 331 for a 95 Boss Mustang it is equipped with a blower . It made 450hp at the wheels. Very fast.
Don
White smoke is definitly
antifreeze. Head gasket more than likely.