When I was looking at buying one I spoke to Porsche Chester and they said it didn't matter on the age of the car (although the one I was looking at was 52 too) as long as it passed the Porsche inspection then they would warrant it. At the time they were offering 2 years for around £1700, as all the OPC cars come with a 2 year Porsche warranty.
Like you said the secondary warranty companies wont insure to the correct amount when I rang around the max they would warrant was £5000 per claim and the prices were insane. If the engine went you need about £10k for a new engine with parts and labour. Which just wasn't worth having. They know fine well that these cars do and have gone bang in the past so no warranty companies will warrant it up to the amount you would need to sort it correctly. So you do need to be careful.
Unlike the BMW indies the Porsche approved service centres are about as good as it gets and Porsche will hold their warranties to these centres, they are very well respected and any potential buyer would see approved centres on par with Porsche dealerships. In terms of RMS they have developed a technique to replace it without taking the engine out which makes it much more cost effective. So it is done at most service intervals.
Most is scaremongering tho! Dealerships and specialists know fine well what the problems are and will make sure and ticked off the list within reason. Like they wont take half the engine apart to make sure the block is ok. But the more common problems will be checked. As long as it is looked after properly and it is serviced rigerously it will be fine. The problem is a lot of people buy them and cant afford to have them looked after properly or dont run them properly and they go bang! Which is why it is a risk buying a used one.
The ironic thing is that it doesn't cost the earth. Very similar to the M.
Like you said the secondary warranty companies wont insure to the correct amount when I rang around the max they would warrant was £5000 per claim and the prices were insane. If the engine went you need about £10k for a new engine with parts and labour. Which just wasn't worth having. They know fine well that these cars do and have gone bang in the past so no warranty companies will warrant it up to the amount you would need to sort it correctly. So you do need to be careful.
Unlike the BMW indies the Porsche approved service centres are about as good as it gets and Porsche will hold their warranties to these centres, they are very well respected and any potential buyer would see approved centres on par with Porsche dealerships. In terms of RMS they have developed a technique to replace it without taking the engine out which makes it much more cost effective. So it is done at most service intervals.
Most is scaremongering tho! Dealerships and specialists know fine well what the problems are and will make sure and ticked off the list within reason. Like they wont take half the engine apart to make sure the block is ok. But the more common problems will be checked. As long as it is looked after properly and it is serviced rigerously it will be fine. The problem is a lot of people buy them and cant afford to have them looked after properly or dont run them properly and they go bang! Which is why it is a risk buying a used one.
The ironic thing is that it doesn't cost the earth. Very similar to the M.
happy cleaning 
