I've got to reach back over 20 years to remember the front frame configuration from my '41, but as I recall the front rails have bulges for spring pockets. If I'm remembering correctly this will make it hard to do any of the typical aftermarket crossmember kits.

A couple thoughts come to mind and will keep you in the family of brands. There are two crossmember assemblies that are pretty close on width, and are mostly self contained, the AMC Pacer and the Mopar Aspen/Volare. The Pacer has a rack and pinion, but wouldn't be that hard to adapt a cross steer arrangement.

One alternative on the frame might be to section in some straight box section steel tubing to replace the spring mount area. You could also whack off the entire front clip and build all new, but then you'd also have to work up core support, and front sheet metal attachments. Less work if you just took out the pockets.

Here's an article that deals with installing the Pacer in an early '50's Chev truck that will at least give you a flavor of what's involved. http://www.chevytrucks.org/tech/ifs.htm His advantage of course is that his stock rails are already pretty much straight.

Some might go with the old standard of a Camaro/Nova clip, but with the 460 you could have sump issues unless you're really setting the engine far back.