Without knowing what electronic ignition box you have on there I hope you didn’t get your hands on one of the old mopar boxes that had a built in rev limiter in it. I fought that issue back in the 70’s.

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