use side count
With those rules, you should side count 6s & 7s & 8s.
So, if you have 78 it all depends on penetration and # of 6s left. If 1/2 the deck is dealt and 1/2 the sixes are gone, say double deck...that would leave four 6s and fifty-two cards...or a 1 in 13 chance of getting the 3-1 payola. that leaves 12 in 13 other possibilities...with ace showing and a TC of 0, you have a 4 in 13 chance of losing outright.
The remainder 8 or 13 with ace showing does not look good for you.
if you would consider using this sucker bet, I'd strongly encourage you to side count the aforementioned cards...