You could go two way in my opinion: Find the most unloved Disco and redo everything on it so that you know the vehicle inside and out, or find the most mint 99-01 or 04 D2 you could find and hope that you don't have to do the first opinion.... which you will probably be doing anyways.
I've had 2 Discos, a 98 D1 with known issues, it had a 5 speed swapped in from a 95, and it was a joy to drive and never really had too much issues. In 14 months of ownership I probably put a thousand dollars of love into it. On the other had I have the spawn of satan itself, an 03 D2 who had HG failure, then had a cracked block about 8 months later, replaced the engine, transfer case and then continued to put stupid money into it... I've basically paid halfway towards an LR4 or a Ford Raptor....But I love it, my wife loves it, it gets more looks than jeeps (which there are far too many) and can eat up the same trails that similiarly equiped Jeep would struggle with (mostly because of the driver, though).
I regret selling the D1 and I'm too deep in to sell the D2.
I hope I haven't scared you too much.