He also said 'easiest' and 'just drop in the motor'. So I had to balance these with the aftermarket support when coming up with an answer. While it is true that he can't order any engine parts from Neuspeed or other big tuner, parts ARE available, it just takes a little more research. We also need to consider that dropping in a non-Opel engine is going to take some time and research as well.
So, if he drops in a 2.2l it will be a fairly painless experience for him. He won't need to make motor mounts and have a custom driveshaft made and cut this and hack that. This will give him a BIG boost of power for a reasonable cost and effort. The risk of tiring of the engine swap before it's completed is also greatly reduced.
When it's time to 'sup' up the motor he will still have many options. Want a lightweight flywheel? Order it from UR. Wan't a better cam? Have one ground at one of many places in the US with Opel cam experience. Don't know what cam to get? Ask on this list and you'll likely get a better answer then you'd get from your typical mail order tuner. Want high compression forged pistons? Order them from JE or ROSS or Venolia or Wiseco... Want a better flowing head? Do the research here and on classicopels and have a local shop do the work, or better yet, send it to TGSI. Want a header? Get it from Kirk or TGSI. There is an answer to just about anything and everything one would wan't to do. And the best part is that these custom parts often cost the same or less than similiar parts from the import tuners...
If this isn't enough, and I can't believe that it wouldn't be, there are MANY parts available in Europe off the shelf that we don't get here. RISSE in particular has lots of stuff, it's just not cheap. It's not any more expensive then the ricer parts here in the US.
And best of all, I consider the wealth of QUALITY information available for free from people like Bob to be more valuable than having a dozen sources for every part. The amount of confusion and mis-information in the import world in particular is so great that I would avoid it like the plague. Yes, there are many import people willing to support you but many just want to sell you parts.
JMHO
-Travis