The solution is simple, quit throwing good money after bad and use it as
woolie suggests to buy a Caravan to do the C206/210 work and the PC12 for the piston twin work.
Flogging a dead horse is well.....flogging a dead horse.
When I win the Lotto I am going to do what a discerning Sydney gentleman has done, buy the nicest cleanest C310R I can find put it the shop for a top to toe bare metal restoration to original mint condition, new transparencies the lot, park it in it's own airconditioned hangar and wheel it out on the odd Sunday, maybe just to look at it and give it a bit of a polish, show it in the vintage concours d'elegance or go for a trip to the vineyards for lunch, good wine and a snooze then dawdle home the next day.