I think you'd probably be way in over your head with a V10 in the long run. Pretty sure the little things will keep adding up and make things a pain. For instance, the gen 1 engine controllers can't be tuned (easily at least), so you may have some issues there. On top of that I'm not sure the engine will run correctly without the rest of the vehicle electronics (instruments, etc.). Plus you'll have to come up with your own custom exhaust since I'm fairly sure no one makes anything of the sort off the shelf (might be able to use SRT10 truck manifolds though).
I went with a 5.7 swap myself and it can be done a lot cheaper than some people make it. I originally went with a carb swap because I didn't want to spend the extra money to update the whole fuel system to high pressure, but I've since swapped back to EFI (Megasquirt) once I got a job out of college and had some disposable income. My engine had a trashed cylinder from a dropped valve seat, so in the end I had the bad cylinder sleeved and replaced the bad piston and head. All in I had the car on the ground running with a carb for maybe around $5k (cost of engine, machine work, swap parts, etc.). A lot of that money is just little parts adding up (things like gaskets and bearings that aren't really aftermarket yet, so the local dealer is happy to screw me, belts, pulleys, etc add up in the long run as well). I splurged a little as well with a set of headers, so you could do it even cheaper with stock exhaust. I didn't have any electronics or wiring to start with though, so I bet it could be done even cheaper with a junkyard takeout since you'd mostly just need swap parts (motor mounts, oil pan, flywheel/flexplate, and whatever your engine might be missing).
The nice thing about the Hemi over the old small blocks is the potential in them. Sure you can get an old small block to 400-500 hp, but you have to build them pretty stout to get there and wind them pretty high. You can get a 5.7 to 400 with just a cam. The newer engines are just more efficient, end of story.
