Cooling issues, could use some advice

Like I said, we'll have to agree to disagree. All of your points are valid in theory. IME with street and race vehicles (road, desert, vintage, drag, etc.) they don't always work out that way. And as I've stated more ideal would to not be in front of the radiator, but if that's where it fits then do it. Just try to place it at the bottom of the radiator rather than the top.

Engine oil absorbs roughly 1/3 of the BTU's put into the engine as fuel. Without a cooler the oil loses it's heat in two ways, radiation - mostly thru the oil pan since it is the thinnest, and conduction thru the block into the coolant. Start actively cooling the oil and both of the other "outputs" will be reduced. So cooling the oil will reduce the thermal exchange load on the radiator before we even start considering what the change in air flow and temperature will do at the radiator. Next look at the delta-T across the oil cooler and you'll find that the 'exit' air isn't all that much warmer than the 'inlet' air, especially when you consider the temperature of the 'inlet' coolant. So the delta-T across the radiator isn't hugely impacted.

I'm not convinced that not over-heating with an open hood directly points to not enough grill opening area. It certainly points to a lack of low vehicle speed air flow thru the engine bay. But is that the grill opening not being large enough, too small of a fan CFM, bordering on too much restriction to airflow thru the engine bay behind the radiator, or?

Before we get into all of the crazy or extreme ideas I'd like to see some response from the OP on the basics that I & others have asked about.