The KB piston you listed is heavy, but if it is the same weight as a stock piston and pin you can skip balancing the motor. If it is not the same weight within a few grams, then balancing is a must to keep the motor from shaking badly. I would use this piston on a cheap rebuild, very mild performance build. The rings are 5/16 which will cost power compared to 1/16 rings used on most newer pistons.
A good quality stock replacement damper will work ok if you are staying under 6,000 rpm or so.
On the stock pushrods, they can work ok provided the rate of lift on the cam and spring rate aren't too high. They are on the weak side, and the stock rockers will not provide advertised lift because they aren't a true 1.5 rocker. There is enough travel in the lifters to handle more than .010 cut on the heads.
To measure head CCs a cheap syringe from a drug store, plastic plate and grease to seal it up and you are in business.