Budget wont quite stretch to a gen 2 unfortunately.
The 2.7 is slow but has incredible handling and is a pretty solid all round motor, IMS failure is incredibly rare and even though it suffers from bore scoring it does not to anywhere near the level of the bigger 3.2/3.4 version. Apart from that check condition of radiators and when coil packs were last changed.
If going to the S variant, highly recommended by the way then of course the risk of IMS/Bore scoring increases. IMS is very rare, Hartech reckon IMS failure effects something like 0.2% of cars and generally any car with over 50,000 miles if very unlikely to ever suffer such a failure as the seal would have worn down by then and will be lubricated by engine oil, for a more in depth explanation give them a call.
Bore scoring is the worse enemy of the gen 1 cars, particular the 3.2, 3.4 and 3.8l engine but engine you can avoid it, by getting a boroscope before purchase, any competent garage can do this, just need the car on a ramp, take the plugs out and stick a camera down the holes, also good for viewing spark plug condition and coil packs whilst at as a spark plugs condition can tell you a lot about an engine and how it was driven. Most owners should be accommodating of such an inspection, especially an enthusiast as long as your paying for the owners petrol and cost of the work even if you don't buy the car I think is fair.
Once you have a car that is score free I feel I have pretty much discovered how to prevent it:
- Change oil with Porsche Spec Mobil One 0W-40 every 6000 miles
- Only fill with Vpower, Nitro, Optimax whatever Shell call it
- Keep revs under 3000rpm until water is nominal temp
- Keep revs under 4000rpm until oil is upto 90c (nominal temp)
- Use the car at least weekly, daily if possible
- Drive it how Porsche intended (when warm)
- Avoid flooring it from a standstill if you have being sat in traffic
- Change plugs every 10,000 miles and coil packs every 20,000
- Improve the cooling system if you can, some cars support an additional 3rd radiator, DO IT, DO IT NOW!
Probably a bit OTT but my car was score free when I got it at 24,000 miles and is still score free now at 56,000 miles.
I think Porsche biggest issue with scoring is from their 20,000/2yr service intervals and the fact most people who buy them never actually drive them and just drive around at 30mph or sit in traffic jams.