I recently added a kit to my inventory to rebuild the 1970 GM 1233464 metering valve. This valve is similar to the 1967 - 1969 3905525 valve, bit it doesn't include a large hex nut plug to keep the internal parts in place. The internal parts are completely different, too, so the kits don't interchange.
As usual, I provide both disassembly and rebuild instructions. The rebuild kit includes a number of custom-made parts, but not the rubber dust cap. I'm still trying to find an inexpensive way to reproduce the cap. The rebuild kit costs $12 plus shipping.