buying a 92 corrado g60 w/swap done

Tomorrow I'm going to check out a 92 Corrado which used to be a g60, but now has a vr6 in it, taken from a passat. The guy says the car has 130k on it, and the engine has 50k on it, but I don't think he has any way to prove this. Can anyone give me a good price for this car if it runs/looks smooth? And also tell me what to check to make sure I'm not buying a lemon? (Will anything be different from a stock SLC?)

Heres a couple of thing you could do first get yourself a compression tester and test each cylinder, its really not that hard, second:jack the car up and check for leaks ie, coolant, oil... third since you arleady have the car on a jack check the brakes, lastly take the car for a test drive .....But the best thing to do when buying a used car is take it to a shop and have them do a full inspection its really worth the money.