Getting one completely stock will likely end up costing you more, like it was already said those mods are fairly minor and half of them are good to do to these cars anyways (like the new exhaust & wideband).
If the body is straight and it's rust-free on the frame then I'd say go for it if a mechanical inspection turns out good (compression test, etc).
edit: Also since he mentions saving his house & has a million tags in the ad it sounds like he's desperate to sell it quickly. Since these are tough cars to sell quickly for full value, if you show up with cash in hand he'll likely take a bit of a lowball (bring full asking price, but split the cash so you have your offer in one pocket and the rest in another).
