Thank for posting. An optional gear spread from a GM T-10 C-1 would require an interesting ‘main drive’, the .490 lift camshaft, a Don Sullivan profile (?) or perhap Jack Engle (??), seems low even for ‘back in the day’. This carb was widely used on pre-65 FE’s, seems it would be sluggish ‘off the corners’ for a 289 CID.
Love these old docs!