There is no end
There is no end to great debates.
I have built two 350's to the limit and they realy do run. Rember Grumpy Bill Jenkins of the seventy's.
I currently have a 400 I am toying with.
The overheating is a problem. Yes you can run the 383 at higher temps.
The 400 will blow the head gaskets right off it.
Besides that high temps do not lead to performance.
It is not the size of your cooling system it is the water jackets and head design that make the differance.
First bring all water ports to gasket and where possible try to enlarge them.
Use an oil cooler and a trans cooler of extra size.
I love that willy's wish I had one.
Keep the new Hemi is a Mopar Fopar.
Like most things with crysler corp when they build somthing good they stop and redesign it into trash. Sorry They stoped building real hemi engins a long
time ago. good luck guys Lou