I went thru this last Winter and I ended up buying them from Summit on my pro shop account during their 20% off sale late February or early March. It wasn't anything they stocked so they dropped shipped them straight from Weld Racing to my house for free.

1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time