Small Block Oil Pick Up Tube Question

In a standard volume pump, the pickup size is not really a problem. When the high-volume pump is used, the inlet size which is the same as the standard volume, becomes the restriction. That was why Milodon had the cover-fed version. That is still the best path, and not hard to fabricate but as noted - you need the oil pan for it.
So the question becomes do you really need all that volume?
In regard to the the modified pickup - if it could be done reliably, some team over the past 50 years would have done it. I would be careful and support that new tube with couple brackets to the main studs because it is thin, and IMO will fracture. The coupler is probably not the best idea either. Have a welder join the threaded end in the pump to the tubing.