I don't know about Mark. But a couple of slant six cars of note. When Dale Rose was alive, he would run his Plymouth Arrow both in the slant six class, and the "heads-up" 10.0 class (usually the only non-bigblock car). Will Burns 67 Barracuda has run low 9's (1/4), Several slant cars in the 10's.
Back when I was younger I had 4 bracket cars (one for each bracket)
65 Valiant 170 slant six for B-4..... would run low 16's
65 Valiant 273 V-8 for B-3... 12.0's
68 Merc Cougar 440 Mopar. B-2..... 10.80's
Front engine dragster 302 Chevy. B-1 ... 9.90's
All foot brake cars, and did well with all of them except the dragster
More recently, my 66 Cuda with a 170 slant has done well before I sold it. would run high 12's-low 13's at 3200lbs, street legal except slicks and open exhaust.