the "traditional" Perkins transplant into old landies was the rather older 4.203 (4 cylinder, 203 cu inches). The direct injection Perkins in the Maestro was a much more modern unit. I'd have thought it'd be trickier to fit that in a landie as it's a transverse front wheel drive set up. Not to say it was never done of course as there are plenty of smart people !
Yes, the 4.203 was the usual engine of choice
A couple of companies manufactured conversions for the Maestro diesel (inc bell-housing adapter)
Milner Engineering(?) springs to mind
A few ‘series 1’ Range Rovers also got a Perkins diesel; the 6.354!!!!!
It was a very tight squeeze longitudinally, having come from Combines
Plus, the ‘York’, as used in the Ford A-Series