Hmm, I'd still want the above questions answered: you can do some remotely: HPi (actually, use Mycarcheck, tick the £1.99 service which is excellent. Only advantage of the £9.99 one is it checks outstanding finance, which we're not worried by on our cars). MOT History (just Google it and make sure it's the .Gov site).
My hunch is: there will be other issues but if basically clean and you're pretty handy, have the space, can afford the time and it'll be a keeper, it MIGHT just be worth doing.
Even so, allow for: G13 coolant, full timing belt kit with water pump, head-gasket set, I don't know about head studs? Manifold seals? Exhaust seals? Oil and filter, valves (let's say half of them), allow for a head skim or at least know you can get it checked. You might want to do the oil pump / balancer chain set and tensioner kit at the same time. The latter needs its own special tool to protect the casing seal.
You'll need the VW PD engine timing tool set (ebay, cheap), the tensioner pin-spanner (ditto) torque wrenches that cover the correct range and possibly an angle gauge, which you can improvise.
You might well decide it's just not worth the hassle. I can't stress enough the need to factor in a £££ value on the risk factor (or contingency if you prefer). My gut is you could easily end up at £400-700 in bits, plus purchase (£350) plus risk factor (£500) plus time. Let's say £1200-1500 plus your time realistically.
If you've seen my Bale or Bounce Back? thread, you'll have seen how quickly the costs can shoot up, and that's for me, in the trade with a decent workshop, a back-catalogue of tools and useful bits plus a 'pragmatic' outlook on what will do the job
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Would I take it on? I'd want a lot of pictures, to know it's got the right history and ultimately, will be the right car at the end of the project. When you buy a car for £350, it seems greedy asking for the history or that second key. Come to sell at £1500-1800 in a year or two and your buyer will absolutely want these things. In short, only spent your time on the right car. This might be it.
If only I listened to my own excellent advice ?