Comfort? LOL. I drive around in my 109. Heck I drove it the 45 minutes to work this morning and will drive it the 1+ hour home. I will say I am trying to keep my trips under 4 hours each way these days. Just because apparently I have ADD and a 4 hour trip is now 8 because I had to stop and do something else.
Anywho, new suggestion: Get a decent 110 LHD. Whatever engine is in it...whatever. While over there, take the time and get the interior and axles how you want them. Import the truck. Ditch the engine and trans and install a GM Gen 4 V8 (5.3 or 6.2, whichevs) with the 6 speed automatic.
There. Power problem solved. Should return low 20s on the interstate since the cylinder delete function will still be active but when you want some grunt, the skinny pedal will actually do something. And 6 speed auto...I mean, 6 speed auto!!!
That would be my suggestion. Lots of little goodies and whatnot over there. Don't be afraid of a NA diesel. The 2.5 NA diesel is somewhat popular with the series crowd and the stubby LT77 could also be sold off with relative ease. Possibly install a 1.2 Defender transfer case while you are over there. There are some slight differences between the disco 1.2 and defender so, might as well do that conversion over there. Oh and before you bring it in, buy a couple sets of steel wheels. Install Michelin XZLs on them. When the truck is in the states, sell those off and put some alloys and 255/85/16 tires on it. Oh and dig around in junkyards for AC bits. Easier to get that mocked up/installed over there than trying to source parts here.
Is it the right path for everyone? Probably not. But it is a suggestion. You wanted suggestions. There is mine.