I've been fighting a severe wheel hop problem on my Zipper for several years. Changed tires, balanced wheel/drum together and fiddled with the friction shocks. As a last resort, I sent the wheels to Woody's Wheel Works in Denver (303-936-0232). Turns out the 1935 16" wheels had flat spots and were out of round. Woody's repaired the wheels and I balanced the wheels and brake drums as a single unit. Also put new friction pads on the friction shocks. BINGO! The car ran straight with zero wheel hop, even on crappy roads. After 11 years of playing around, I have a car that is finally finished to my satisfaction. Now on to my next project; 1.8 SOHC / four speed powered Model A Huckster.
Amazing how often those old wires are out of true isn't it. On my old bkes I used to true the wheels once a year they didn't weigh as much as a car and I wasn't using 60 year old wheels. Glad you got it worked out.