Well I believe he said the head were going on a 350.
"...Don't think there are many '69 400 2-barrel restos going on."
I was referring to the possibility of selling the #46 heads, at sometimes in the future, should he ever wanna do so. Those heads came on several 2-barrel 400's. Also came on one Bonnie 4-barrel 400 and some 4-barrel 428's, according the info on the Wallace site. Just assuming that there are not many numbers matching resto builds, requiring the '69 #46 heads.
But there are lots of possible buyers for the popular big valve heads I listed. Those heads came on lots of Birds, Goats, & GP's. And they are used on lots of performance engines, in cars that did not come with 'em. Just a much larger market for those popular high compression big valve screw-in stud heads.