I'm getting really bored of repeating myself about this, but for god's sake stop peddling that crap.
You CANNOT fix the IMS issue unless you buy a car with either the Mezger engine, the DFi engine, or an earlier air-cooled engine in. End of.
If the IMS fails, your bill will be around £5K AT LEAST. The engine essentially self-destructs. You may get away with a £5K bill, £7K is average, could be £10K easy.
You can upgrade the IMS to a later Porsche design, but this does NOT guarantee that it won't fail. The same weakness IS STILL THERE.
You can change the IMS to a third-party one, like the LNE IMS Retrofit, BUT EVEN THEY DO NOT GUARANTEE THAT IT WILL NOT FAIL. The parts alone are $649, plus you need the install kit which is $250, so that's $900. Make that £900 if you include shipping, VAT and import duty and you won't be far off. If you can do that yourself in your garage then you're a better mechanic than I. LNE suggest that it will take between 10-14 hours to replace the IMS bearing, so at £50p/h (I'm being generous with the labour cost), then that's another £500-£700 on top. Call that £1400 to £1600 then, and you STILL have the risk of IMS failure.*
In short, there is absolutely no way to 100% ensure you do not get IMS failure with an M96/M97 engine, REGARDLESS OF WHAT YOU DO. It irks me that I'm having to write so many capitals, but how often do I need to repeat this mate? You're a knowledgeable chap and have more than a passing idea on this subject, but handing out wrong advice could end up with someone getting burnt.
LNE LMS 101
*You can of course do this during a clutch change and save some labour costs. Most people do.