As far as I know the quickest slant six "door slammer" is Will Burns, from Va in a 67 Cuda
9.65 in the 1/4 mile, and hurting the engine just after the 1/8 mile mark. He is a member here, and maybe will post more/correct info.
I've heard Will's slant six at the Dinwiddie VA track. Serious stuff and earmuffs definitely required! It is one nasty and fast slant six to say the least. A great guy as well.