Keep looking but you have your thoughts in the correct direction...if you can't find shorties to fit, just keep the stock exhaust manifolds. The fit problems with the exhaust underneath the truck are not worth the gains with long tubes in my opinion.

With the carb/intake, stay small. Around a 600cfm with vacuum secondaries, and a conservative dual plane low rise intake. Most 460's had 4bbls as you know, and I would not hesitate to get one of those intakes at a good price and use it. I would get a new carb though. Too many vacuum ports to plug off on the original 4bbl and it was mainly a emissions carb.