Up for sale is a pretty nice single groove water pump pulley, p/n- 1231724. It has been media blasted, primed, and painted gloss black. It's 6" in diameter, and correct for the '70 Buick 350, as well as many other pre-1970 Buick engines without A/C. I'm asking $30 + shipping.
Sorry, meant to reply to this - been so busy getting ready for BG. I don't have one but planning to add HD cooling to my no AC car which takes the 2 groove pulley anyway so this was just in case those plans change. If @JohnnyS needs it, I'll pass. If not, we can revisit.