Pretty sure Rod carries the ' cookie cutter" 4 inch arm kit as well, not just 4.125 and 4.250 kits.

69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, low 10.30’s 1/4
1.41 best 60 foot
6.56 at 104.17