[fred cook]

If your pistons are from a matching weight range, they should be ok. Still, it is easy enough to weigh each one on a home scale that reads in grams. I bought a new set of Mahle pistons for my engine's rebuild and found them to be + or - 1 gram variation. Close enough for a street engine! The rods should be balanced for total weight as well as end for end. That is, all the small ends should weigh the same and all the big ends likewise. Someone with a crank balancing machine will have to check it as both static and dynamic balance will have to be checked. If you decide to go the whole route and balance the clutch and flywheel, do so separately. Balance the flywheel first and then the pressure plate. The clutch disk can also be done separately. That way, if you blow a clutch, all you will have to rebalance is the replacement for the damaged part. Good luck with your rebuild!

PS: If you don't already have it, get Wayne's 911 engine rebuild book.