Running Hot

It doesn't matter that the fan is only an inch from the radiator--get a shroud on it. You're only pulling air through the radiator where the fan is, nothing off to the sides, above or below the fan. A shroud will funnel the air out the back of the shroud, pulling air through the entire core.

Get the biggest 7-blade fan you can as well. And I don't mean to be insulting when I type this--make sure your fan is on the right direction. I've seen it happen.

Seal the bottom of the hood to the core support with a rubber gasket of some type (many cars used a simple rubber flap) and make sure the shroud is sealed to the core support so the fan isn't pulling air from the perimeter of the shroud.

What are you running for coolant? I highly recommend Water Wetter.

My daily driver is a SBC-powered '62 Suburban, and I drive it in all traffic without problems. 4-row copper-core radiator, 7-blade clutch fan, 50/50 antifreeze mix (though I'm going to re-evaluate that), and a 160-degree thermostat in the summer, 180-degree in the winter. I don't have the shroud on it yet. The fan sits back from the radiator an honest 8 inches, and at idle that 7-blade, 17.5-inch fan will suck a piece of notebook paper tight to the radiator. I expect that once I get the shroud in place, it will suck small birds out of the air.

What t-stat are you running? The t-stat opens at a given temp to regulate the water temp. I like to run the 160-degree in the summer, because it lets the coolant circulate at a much cooler temp... when I get stuck in traffic, it gives me an extra 20-degree head start on keeping things under control.
I also drill a small 1/16-inch hole in the flange of the t-stat, so any air in the block will bleed out when I fill the radiator.

Check your system for trapped air. Check and make sure the used radiator you have isn't plugged. If a couple tubes are plugged, you're losing cooling in a large area.

Be sure your hoses aren't crimped or collapsing.

Also, check and make sure there isn't sediment in the bottom of the block's water jackets. I've seen engines where the jacket plugs were pulled out, and nothing came out--the sludge had to be moved with an ice pick before the block would drain.

Also, a switch to an aluminum radiator would be a big help--aluminum transfers heat much better than a copper core rad: in a copper rad, the tubes are copper, and the fins are copper, but they are connected by a lead soldier joint, and lead is a horrible conductor of heat.

Finally, if you're running an auto trans, get an auxiliary trans cooler, or you might think about running an oil cooler.

-Brad