Back to the oil pump issue. Will the GMC pump bolt right up to the Chevy block?
And then it’s just a matter of plumbing that pipe to the galley, and modifying the pan to work with the oil pick up?
The GMC pump housing is MUCH larger that the Chevy, and I'm pretty sure the volume is higher. Since I have examples of both pumps available, I'll post a photo shoot of the two in a side by side comparison once there's enough daylight to get good photos. It was a pretty common modification back when stovebolt engines were used in round track racing. The GMC pump mounts the same way- - - -with a single tapered setscrew in a bracket on the block. It's definitely NOT a bolt-in swap! The oil pan modifications are needed to clear the pump housing, not the pickup.
Jerry