keep your eye on US ebay,complete engines sometimes come up and shipping is not as big a deal as it used to be (you gotta win it first though).A couple of years ago I won a 360 engine for $395 US,had been used for dirttrack.Got it back here,original piston(sloppy),tight bigend,smooth gearbox,and gaskets made from newspaper.Orig twin spark points ignition,did the barrel for a 1st over piston she's been going great ever since
.If you find a big one I'll take the 250 off your hands;I reckon they are a great engine