Vlaue of original engines???

Does it hurt the value of a car with it's orginal engine beefed up, like port and polish heads, new camshafts and such? b/c i'm looking to buy a 79 trans am with a 403 that is matching #'s. But it only has 180hp and i think around 300tq but not quite sure.

If the car is "collectable", yes, it will detract from the value. A '79 T/A is only a REAL collector car if it's the 10th Anniversary SE. It would be silver with a silver leather interior if that's the case. The T/A 6.6 and WS-6 cars are next in line. Since it's a 403, it's not a T/A 6.6 car (they were all 400 Pontiacs). It could still be a WS-6. Does it have rear disc brakes? If not, not a WS-6 car... BTW, the average '79 says "6.6 Litre" on the scoop. A T/A 6.6 car says exactly that on the scoop: "T/A 6.6", and nothing else.
'79 was the highest production year for Trans Am (over 100,000). If yours is the plane jane with the 403, it won't hurt a thing to modify it. You could actually enhance the value by chunking the 403 and putting a Pontiac 400 or 455 in it. Pontiac people respond much better to Pontiac engines. Ask me how I know this...