In the market for a used 1975 164 30F engine. I am open to any offers. Thanks.

Unless you are lucky enough to get a documented low mileage runner you may get an engine with issues. You should pull yours and check it out, bores dont wear much (deglaze), new cam and lifters maybe cam brgs, c/rod and main brgs, timing gear is a must even with changeover engine, gaskets and seals. Crankshafts rarely wear below tolerance, cut seats reface valves. Your oil pump is working ok, this will allow you to diagnose your valve train lubrication issue. The cost of parts and machining would be offset by cost of used engine of doubtful condition. You would still have labour costs, it would be a great learning curve if you have knowledgable help.