Firebob is correct, start with adjusting the shifter itself. When you bought the new Hurst shifter it would have come with a plastic pin that you push through the notch in the shift levers. Adjust the shift levers by moving the nuts on the shift arm trunions until the notch in each shift lever lines up perfectly with one another.

Basically loosen the trunions on all shift arms, push the plastic pin through all the notches and tighten down the nuts that hold the trunions in place.

Then do a cluch adjustment and I'd be willing to bet you'll solve the problem. Also, and this goes for all Muncie 4-speeds. When attempting to put the car in reverse, always go to third gear first, THEN into reverse. This process re-aligns/resets ALL the syncros inside the trans thus allowing for a "grindless" reverse gear. A trick I've seen MANY old school 4-speed guys use and it saves wear on the syncros!