This may help you out info wise. I feel bad posting a rival forums address on here though! They have helped me a lot with my cruiser over the last couple of years!
http://forum.ih8mud.com
And the only online parts supplier worth using. Their Electronic parts catalog is second to none!
https://www.amayama.com/en/
My 109V8 must have been specced up by its first owner then because it was a cab chassis but had a full headlining, plus pillar trims, door cards and high back deluxe seats!
My 1982 sales brochure has a county spec list on the 109V8 page but only has pictures of the full fat station wagon, so can't comment on a 3dr hardtop.. It also shows the 88" county spec with everything that Lewis mentioned bar the rostyles.
I run an Auto Meter pyrometer albeit in my 70 series Landcruiser (dirty word, sorry!) and it's excellent. Cost a lot but then again quality only usually hurts once!
I have the Dremel versatip and it's brilliant! It's easy to use and comes with a good selection of tips. The exhaust thing caught me out the first time when I melted the surface I was soldering on! I now use the exhaust to shrink the heatshrink.
I have 240v irons but to be honest I use the Dremel one more.
A 13BT could be worth a look. 3.4 turbo, direct injection. They make around 110/120hp in stock form depending on the version. Heated intake instead of glow plugs.
A little on the clattery side being DI but good strong motors otherwise.
http://forums.lr4x4.com/index.php?showtopic=34510&view=&hl=&fromsearch=1
Might an option worth considering.
Have you considered Toyota 4cyl diesel? Or are they too pricey?
In NZ a company named forward specs offered this conversion (Nissan LD28) into a defender and mated them to LT77s I believe. I think they were contracted by the NZ Air Force to fit out their 110s . There was one for sale on trademe.co.nz not long ago.
Common to see series trucks with them here too. Great motors, some folks have had success turbo-ing them
It's probably a combination of the door hinges sagging and tub perhaps sitting a little high. Does the tub have any packing under it? Similarly, do the door hinges have a lot of play in them?
If it's the door hinges, make sure to adjust the catch afterwards so it shuts again!