I would personally buy a set of aluminum Caps off our ember that sells girdles or see if Best Machine has them. Way better choice if you ask me. I ran a set of their (440 source) Billet caps and they of course needed Machine work. My block made 275 eight second passes and was split up through the mains when I took it apart to freshen

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