The Victor gaskets are cheaper, that's why shops use them. They are the same design as the garbage OEM gasket, so I strongly advise against using them. The Fel-Pro gasket set will eliminate the problem, as long as you used thread-lock on the lower intake bolts. The issue with these engines is a very low torque value on the fasteners combined with the bi-metal engine (heads and intake are aluminum and the block is cast iron) and the different expansion rates of the metals. That oil pump o-ring can be changed by removing the throttle body and coolant transfer tube as an assembly (as there are two small hoses from that transfer tube to the throttle body that are impossible to reach). Like I suggested before, install both the o-ring (Fel-Pro 70800) and a small block Chevy distributor gasket (Fel-Pro 70194) between the top of the block and the oil pump drive as added insurance against future o-ring failure. I hope your mechanic friend learned a valuable lesson about not doing so.