I'd be looking for a 4bt for that rig.
I've been keeping a lazy eye out for one.
Not really looking at the moment, but if one popped up and the price was right...
I don't know why but the 1.9 ALH motors used in the VW diesels are also appealing to me. Very light weight compared to a 4b and can easily be tuned to make more than adequate power for my use.