Hi,
I would say do you really need a fully reconditioned engine?
2.25 litre engines come and go all the time, people are always trying to get rid of them, quite often in a good condition, or at least running smoothly. All I would say is that make sure you get a 12v if you have a 12v vehicle, or 24v if you are FFR.
You could pick one up from online auctions with bids starting at 99p. You may want a fully reconditioned 'New' engine, though personally I would try a £10 engine before spending £750 on one.
As for answering your question, I do not know if that would be a good buy. It would not be compared to another 'running' engine, though it may well be compared to other places selling fully reconditioned engines.
On a plus side, it would be better having being fully reconditioned by the MOD and sold through Witham than anywhere else.