Well, the bellhousing is on the gearbox; and the drilling on that should mate to the stud hole patern on the block.
Yes, there are a number of different bellhousings; I dont know about the early Series 1's & 2's but there were two varients for the S2, with different clutch mechs in them; and another when they went to the S3; the six pots also got thier own bellhousing; then early 90/110's got yet another, becouse they used the LT77 box.
HOWEVER; the stuf patern drilling on the 2.0; 2.25 & 2.5litre four pot engines SHOULD be identical, and common whether petrol or diesil.
Its even the same on the 2.5TD, and the 200 & 300TDI's......
Are you certian that it's a 2.25 engine?
Is it a diesil?
If it's a diesil, and likely a 2.5NAD then could be be a LDV Sherpa varient, or Austin FX taxi, and I think there was somthing else used them too;
BUT, only flange patern difference I'm aware of is that one of them had an extra location dowl or lacked an extra location dowel, in which case simply solved by removing it.
BUT; the conundrum I'm pondering is whether it could be you have an engine with an adapter plate on it to attach it to a Ford MK4 gearbox, or to the bellhousing for a Range Rover four speed or something.