If the smoke is oil then you would think it has to be either valve guides really really worn, or a broken/worn piston. The motor in the `65 I have had a broken piston (which I saved), It`s broke between the second ring and the oil rings, because the top ring was intact it passed a compression test with flying colors, ran fine but smoked on and off alot when after it was warmed up good. You might be able to read the plugs on that bank to see which cylinder it is.
I have seen too if a motor has had a blown head gasket and the exhaust gets hosed with antifreeze that it could take awhile to bake all that antifreeze out of the insides of the muffler and pipes. It may smoke when you gun it and it heats up baking some out..... Pound on it alittle bit and see if it starts letting up.
If it was fuel related you`d expect it to be on both banks.
