Yes, I can post a pic or two but it won't help you much. I have a 26" OE style radiator with shroud in an E body with a Hemi. Using an HD clutch with a cut down truck fan. It really moves a lot of air and doesn't have any trouble keeping the big Hemi cool, even in traffic.

I also had a Hemi in an A body, but I used an aluminum radiator and the Mercedes electric fan on that one. That fan moved a lot of air, too and kept that Hemi cool.

I had always used the Mr Gasket hi flow thermostats in my Mopars, but the last 2 that I have had have failed very soon after install. I now use the Stant Superstat or the Motorad Fail-Safes. They do not flow as much as the Mr Gasket thermostats, but I haven't had any failures from them. I always drill a couple extra holes in my thermostats for just that little bit more flow and it makes filling the radiator just that much quicker. It may slow down the warm up time by a little, but the big Hemi makes enough heat that I can't really tell any difference.

Based on the info you have provided, I believe your issue is air flow at low speed. A fan that moves more air, getting the fan you have closer to the radiator, speeding the pump and fan up at idle, and maybe a shroud with it's correct fan would be things I would suggest trying. And again, posting pics of your radiator/fan for these guys to see would be a good idea.