The bigger problem with the HDi lump would be the electronics but if you go for an 8v jobby i believe there are people moving them onto idi pumps and the same for the 2.2HDi units. much more reliable, less electronics and they can run and veg and much poorer fuels in general and not grumble as much
The LDV's are a good option as most bits are there, most are minibus's anyhoo and would likely need some real metal work to get them good, they have really underpowered XUD's as standard as not many had turbos and other than typical british built rust issues they weren't too bad. Cheap as chips as well and got the look of an old van as well