As noted, there are advances in material sciences since the day your engine was built and although you could mix-n-match various brands of pistons it would be foolish to do so as the actual piston weight can and will vary from source to source due to variations in the initial piston blank and subsequent machine operations. Perhaps, if you don't mind some minor imbalance, mixing would work out but, any imbalance in a rotating assembly will add odd stresses to the parts.
I am reminded of a customer who had bought a 350 crate engine from his gm dealer; upon disassembly, for the purpose of verifying what he had, the off-balance was measured in ounces...not grams. So, apparently, gm didn't think an out-of-balance condition was an issue. YRMV