Are we talking about external overheating (wiring and plastics in the engine bay melting, etc) or internal overheating (excessive coolant or oil temperature, pistons melting, etc)?
Louvres in the bonnet will address the former but do nothing for the latter, since the engine internals are cooled by water and oil, and lose very little of their heat to the air in the engine bay in reality. Relocating the oil cooler to an external oil-to-air unit will reduce the heat load dumped into the coolant and help solve excessive coolant temperatures but do nothing to solve any external overheating issues. For this reason I find it hard to understand how these two measures were being applied to resolve a single issue unless a "scattergun" approach was being used without a full understanding of the real issues at play.
You can bet the GM engineers threw much more resources into getting the cooling right than any of us can muster. They might have been aiming for a lower power output, but they were aiming to achieve it for hours on end in the world's most demanding climates.
As soon as you make a change, even as simple as removing the standard oil-to-water cooler, you have changed the coolant flow distribution around the engine and thrown that all away. You've also started throwing money at a "problem" that might not exist by buying expensive parts that may not be necessary.
If I were in the OP's position I would ignore the internet folklore, leave the cooling system standard but with the largest radiator I could fit, I would then start with a conservative boost pressure and monitor things carefully as I gradually develop it. We're in unknown territory as few people have tuned this engine, and those who have have not left reliable records of the problems they encountered.