I just posted an article that describes how to rebuild the 1970 GM 1233464 metering valve using a new seal kit that I produce. Here's the article:https://www.musclecarresearch.com/gm-1233464-rebuild
Please let me know if any part of the process is unclear or could be explained better. The rebuild kit is available for $12 plus shipping per kit:https://www.musclecarresearch.com/gm-metering-seal-kit-2
Orders can be placed directly from my web site. Just add the item to your shopping cart and click through the "Checkout" links. Payment methods accepted include PayPal, credit cards, checks, and money orders.
Please note that the kit DOES NOT include a replacement for the Bendix rubber dust cap. I'm still exploring my options to see if it can be done economically.