if its a 16v kr its a good base, is the engine running and complete, is he using an aftermarket ecu or got a decent stainless exhaust manifold as the 16v conversions require a different manifold.
the 5 stud conversion on the rear is easy, just change to 5 stud drums i think but not sure what they have done for the front, may have used a 5 stud stub axle or used completely different hubs
im guessing no tax and mot but people normally ask 250-400 for the 16v engine alone with the appropriate stainless steel manifold so if you get a cabby for free you cant complain
haggle your arse off tho mate some people might tell you to f**k off but still at least you've tested the water, but if it looks like a good project get it and get stuck in fella

seats/headlights you can get cheap, might be looking at a fair whack to get a set of proper mint original cab seats or a leather setup tho, if interior has been stripped out you could end up spending a small fortune on the little bits to make it complete
are you looking for a long term project, resto or just a cheap daily?