The 1967 Case 430 had a rockshaft piston seal that was disintegrated and came out in little pieces. I fashioned a piston seal installation tool out of 3" pvc conduit by cutting off the bell end of it and reaming it so that it just fits down over the piston. Seal slipped right on with some lube. I used a piston ring compressor to install the piston and seal into the bore. Everything went well.
Many thanks to: Adirondack Case Guy, Chuck Machinist, Loren, Joe WA, John Sareli, Jim ME, 45 Cole and Gusbratz.