yeahyou can get all the parts from VW, bear in mind that if you decide to replace piston rings and all bearings then parts alone will come to at least a couple of hundred quid.
As for an engine builder I would speak to a local garage and try to find out who they use. Any local decent engine building place should be OK doing it.
Not sure how you can do a compression test with the engine out of the car (any ideas anyone?) but you can certainly get hold of some plastigage and check the bearing clearances. If well within specs then I'd just leave them, as the saying goes, if it ain't broke, don't fix it. This is what I've done with my current engine, just replaced the rings, rehoned the bores and checked all the bearing clearances. Then gave everything a good clean. The engine I started out with was like yours, had been lying about for a while, very manky and unknown mileage, turned out to be good once I'd stripped it down and cleaned it though. Not bad since it cost me £50.
