In the last few weeks I've learned a lot about the differences between 1962 and 1963 VW 1500 engines. Many components were changed at the beginning of the 1963 model year, as listed here in a March 1964 supplement to the VW 1500 Workshop Manual:
I knew that the pistons, cylinders, and heads changed at chassis number
0 064 916, but it was never clear to me exactly how. Now I know.
The pistons introduced in August 1962 are about .060 in. taller than the earlier pistons, and the cylinders and heads were also redesigned, raising the compression ratio from 7.2:1 to 7.8:1. It's something to keep in mind if you're rebuilding an early 1500 engine. Not all 83mm pistons and cylinders are interchangeable.
We were able to use my newly sourced NOS '63 1500 pistons on the Ghia's engine by shimming the cylinders .060 in. Since we're still using the early '62 heads I was worried that the shims might cause problems in fitting the intake manifold, the early cooling tin, and the muffler, but a test fit on the reassembled longblock put my worries to rest. The muffler was a tight fit but enlarging the holes in the mounting flanges slightly took care of it.
I saved the Ghia's three original Mahle pistons and will be on the lookout for a fourth to have on hand in case they're needed for a future overhaul. Here are the markings on them (part number 311 107 101):
This weekend I'll be reassembling the engine, and hopefully the Ghia will be back on the road within a week.