I am wondering if this is a feasible proposition. And if so how difficult of a conversion is this. I'm not sure which Nitro Express cartridge yet, but any suggestions there would also be great. Also, are there any other actions that would work for these cartridges short of a double rifle, I am on a budget.

Trailblazer, yes it can be done. A gunsmith here in Helena built one in 500NE. His name is Dennis Erhardt, his phone number is 406-442-4533. Give him a call, he'll fix you up! Oh, i forgot he did one in 470NE too.

TB,
it is not a difficult conversion. I had one made in 500nitro 3" a few years back. Started off as a 30-06, new barrel, top Quarter rib and express sights, re-cut the extractor. Re-profiled the safety and put a Pachmayr decelerator recoil pad on.
Still my favourite BG rifle.