[Evans968]

My '88 911, purchased with 78k on the ODO, now 25 years later has, 160k. I had a mechanic repair some bad rings at 129k and he did the crank bearings at the time (said the heads were OK). All was well until the timing chain case leak occurred about 5k miles ago, repaired/sealed and cam timing adjusted by a different (competent) mechanic who discovered some sloppy work by the first guy. Recently during a hard DE run, new evidence of oil leak, on the right bank, cam tower to head area. I have removed the valve cover on that side and confirmed that the rocker shafts are not leaking and appear to be in the proper position, possibly never touched by the 129k dismantlement.
So I plan to remove the engine, take it to my current mechanic to remove probably both cam towers for re-seal. The question is how far is it prudent to go down the "while you're in there" path (truly a dangerous path). I have read numerous Pelican threads on this and believe i understand the rocker shaft issue (rebuilding this area on a high mileage engine may require additional machining, RSR seals, etc.
I would like to end up with a reliable engine to a) maintain the value of the car (other wise, very nice), b) OK for autocross and maybe one DE/year, c) leak free. A complete rebuild (new cylinders/pistons) would add about $4k to the cost, so if original pistons check out ok, would lean toward keeping them in. But moving to at 3.4 set is tempting. Head rebuild seems appropriate now.
Any advice you can give would help.
Thanks