Thanks for the suggestions guys. For the moment, I'll skip the Gurkha as it's too rare. Dealer support is suspect. Also at the OTR's there are mostly Mahindra's & Gypsies (of course some people also come in Pajero's or Cayenne's), so if something goes wrong there are others to help.
Shame on me to have missed this thread.
So you want to go the FFRA, LSD, OKBJ way. Hmm....why are you even thinking so much? Just go and buy yourself a new Thar DI (CRDe is good too but not recommended as its IFS is not as easily conducive to modifications as the rigid axle of the DI is). All other mods listed by you are easily doable on the CRDe. Both DI and CRDe share the same NGCS chassis.
For approx Rs 5.5 lakhs, you will get a NEW, rugged 4x4 with full spare/service support from the factory and reliability levels that rebuilt MM540s/550s/CJs could only dream of (not impossible to make them reliable but you know what I mean, right?). This vehicle has UNLIMITED mod potential and the best part is that there is no electronic gizmogiri (DI engine). The last generation of pure, classic, simple, rugged, old fashioned off roading at its very mod-friendly best.
Go buy it. In white. All the best!