Def support the inline mod but when you upgrade is a good thing to think about. I am starting to sway towards this thinking and some of the senior members may correct me.

It’s important to get a baseline of the vehicle as it was designed. Just for a little bit at least. Drive it for a bit if you can. Understand the specs and how it works. See what operating temp you have using an ultra gauge. Check the mileage. Change all the fluids, inspecting for metal bits. Learn the vehicle before you really get into the modifications and heavy maintenance.

Yes it’s boring. Yes it’s lame. But I didn’t do that and I’m paying for it now.

change the front drive shaft
buy an ultragauge
switch to green coolant after complete flush of the cooling system.
change the thermostat to the lower temp specification (research the good one that people recommend)
update some cooling hoses
Research all the how to’s write up’s and tech sections for both D2 and D1. Learning the differences has helped me. I own both.

Start learning about the head gaskets and more specifically the Rover V8 engine.

Get the workshop manual
Get the OTC Land Rover online parts publication. Identifying parts/parts number is a PITA.
Get a lot of PB blaster
Get a good set of extractors....
Get a good set of bolt head extractors....
Get a good set of drill bits....