Hey, how'd I miss this?
Personally, I'm really happy with the Cummins swap. I looked at a bunch of stuff before I tore out the 460 and the 12v was definitely for me. I was at 9.6 freeway and 6.2 around town with the 460. Yeah, all the Cummins guys on the internet will tell you 20+mpg so keep that in mind. I've gotten 19.5 mpg once since my transmission overhaul but I have yet to get any where near that since. Trip to Mexico in 4 weeks so I'll let y'all know.
Is it loud? Sort of, well yeah. Once you start turning the fuel screw it gets louder. Put a quart of 2 stroke oil in it and it'll quiet back down a bunch. I originally used a Diamond Eye exhaust and it had a drone that was obnoxious. Recently got rid of the Diamond Eye muffler and put in a Donaldson 51" muffler and it's almost too quiet. All you can hear is the engine itself.
I've got almost as much money into the Dana 60 swap as I have into the Cummins swap. If I wasn't "wheeling" my rig too hard, I'd keep the 44hd. It is nice not having to worry about the 60 though and running into/over a deer at 60 mph plus a few weeks ago made the 60 swap worth it.
Essentially, you are stuck with the problem of big block vs. diesel. I chose diesel because I found a 12v for $1,400 with a trans attached. I did like the 460 but I had no range with it and that was important because I really wanted to use this rig for travel. I bet you'd be dollars ahead keeping the big block Ford and paying for $4 gas. But, it'd be a lot more fun if you did a swap to your liking.
Personally, if I was you, I'd be looking for a common rail and a ZF-6. If a common rail is too much dough, a ve pump out of a 91.5-93 Dodge is tough to beat.