My take on the oiling system crossover tube for the small block

Boy, lots of opinions/different ways of trying to keep the rods in these things. If your way works for you, that's great.
IMHO...
Chevrolets are very different from Chryslers - they have a main galley that feeds the crank exclusively and auxiliary galleys to feed the lifters and heads. These auxiliary galleys are easily restricted and controlled at the back of the block as to the amount of oil going to these areas, which in turn makes it easier for the system to keep up with the crank oiling. I tried to duplicate this with what I was doing.
A separate auxiliary line, rear to front and feeding the front of the right galley provides a source for oil to the left side in the event I want to provide oil pressure to the lifters. That is the ONLY reason to put oil in the left galley.
I like bushing the lifters. It corrects the sloppy original machining, seals the galleys, wears better than the iron bores especially in a 59* deal and allows for precise control of oil to the lifters if needed. There are different ways of doing that.
I prefer to oil all 4 mains from the right side and do what it takes to seal those mains at the saddle and keep all the oil on the crank.
None of these fixes require or would benefit from running a crossover. In fact, putting oil in the left galley would be counter-productive to what I was doing. Front oiling eliminates that need. #1 main has the benefit of only having to oil one rod. #1 main and rod were always happy.
I do not agree that the mains are the first thing to show problems due to lack of oil. The rods are at the end of the line and the first to run dry when the flow stops or pressure drops. Typically in my experience the rods would show signs of lose of lube while the mains were happy.
Timing can be an issue. Full groove mains should fix that IF the problem is entirely how the crank is drilled. Changing that had zero benefit for me. Eliminating that big pressure dump at the cam journal every revolution of the cam did make a difference.
My steel crank 340s were mostly happy to 8000 with few modifications to the oil system. The iron crank 360s were awful. That is where I was forced to figure all of this out.