Looking for a 993....

[crayzayjay]

Title says it all really. I'm looking for a 993 (RHD as im in the UK). The problem is that there are few cars under 65,000 miles, which i know isnt that much for a 911 but i'm kind of hoping to find one with ~40k, and all those command a hefty premium over the higher mileage ones. It has to manual, and again they're more expensive than the Titpronic models... So really i have two questions for you guys?

1) In terms of mileage, when do you start to say "hmmm... engine may be past its best, or will need more maintenance"

and

2) How difficult / costly would it be to change transmission from Auto to Manual?

Thanks for any replies. I've loved 993's forever and now i just want to find a good one while some are still around.