I agree with the high volume pump scenario, but how do you explain him chewing up a gear the first time with a stock engine, other than having the LT4 cam swap?

 

OP stated: "the first was with a stock lt1 with a lt4 hot cam being the only mod "
My thoughts are:
If only the camshaft was changed, either the manifold is not in the right physical place,
or cam gear ground wrong, or as you suggested earlier, retainer plate missing or excessively worn, or new cam has incorrect retainer plate surface location?

Stock configuration worked apparently, then changed camshaft and problem started?

 

LT1 oil pump drive is mounted under the intake manifold, in the oil valley. Intake positioning wouldn't have any effect on the drive.
But I was wondering if it's possible to have an oil pump drive that's down too tight against the pump causing a bind, like what can happen with a conventional drop in distributor after heads/intake manifold gets a shave. With those, they make shims you put between the distributor and intake. You could do the same with the LT1 setup, but I don't know how you would go about checking the end play from above with no exposed shaft to grab.

 

Had the same problem years ago when I installed the hot cam in my Lt1 Camaro. The oil pump was stock, but the teeth on the drive gear disappeared whiting about a month's of usage. At that time I was able to find a bronze gear and had no more problems. Being that my gear got destroyed while using the stock pump, makes me think that the size of the pump may not be the problem.