they're the same mate. only difference really in the engine bay, and it doesn't affect the engine is the strut top mounts being a different size between mk1 and mk2.

all you need for a 2 litre ohc from a sierra is an rs2000 alloy bellhousing and sump and engine mounts. it's all been done thousands of times before. get along to a few shows this summer and talk to owners.

personally, i wouldn't be looking at such an engine these days. i'd be looking at a more modern engine like a 2 litre zetec. not quite as straightforward, but easy and cheap enough these days and the power and torque available from a std injected unit is superb. needs water rail mods to fit without cutting bulkhead though.