A friend just took a set off of his 74 Camaro and put some normal mufflers on it. Like 52Carl says they were good for about 20 minutes.
You can probably get them cheap.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine