Hard to nail the converter with out engine particulars especially cam and head flow numbers. What does the car weigh? Tires good and not spinning? Radials tend to wear out before the "tread" is done. 7.80's won't be wearing them out though...
Its a full interior 1970 Duster with a hurst shifter with fiberglass hood/front an rear bumpers, front sway bar removed,Full cell and the spare tire is cut out and a thin aluminum was pop ripped in holley blue pump an fram filter. No roll bar/cage. 15x3.5 an 15x10 centerline wheels.
