A bet on big 8 works the same way; to win an 8 has to be rolled before a 7. Big 6 and Big 8 bets pay even money.
I never play Big 6 and Big 8. It’s just a bad investment. A place bet on 6 and 8 is exactly the same as making a big 6 or 8 bet, but with one major difference, the payout. A bet at Big 6 or 8 pay even money but a place bet on the same numbers pays 7 to 6. That means that there is no reason to play big 6 and big 8. I recommend that you stay away from that area of the craps lay out.