The power figure is way off what it will do the norm is around 350-360HP so that would make me question what else he is lying about and the spec is not that good it has a eBay manifold on that just cracks and is not as good as the oem one.
The early cars are getting tired now and are starting to corrode if they have not been underseald, check the rear chassis legs for corrosion if you do go to look at one and the fuel filler pipe as they corrode.