I am not certain but from my understanding the gear height is slightly different as well on a roller motor. Just changing to a bronze gear will not work long term. The placement of the gear on the dizzy shaft is different.
Is the engine together currently? Has the intake manifold been off?
Can you pull one valve cover, loosen one rocker arm and lift out the push rod? Shouldn't take long. If valve covers have not been off this is a great time to replace the valve cover gaskets. Get the modern felpro gaskets that have the metal spine. You will need the valve covers off anyway to prime the engine if it's been sitting for a while. Measure how long the pushrod is and we can figure out which engine you have.
If you have had the intake off did you see what is called the spider in the lifter valley?
Is the engine together currently? Has the intake manifold been off?
Can you pull one valve cover, loosen one rocker arm and lift out the push rod? Shouldn't take long. If valve covers have not been off this is a great time to replace the valve cover gaskets. Get the modern felpro gaskets that have the metal spine. You will need the valve covers off anyway to prime the engine if it's been sitting for a while. Measure how long the pushrod is and we can figure out which engine you have.
If you have had the intake off did you see what is called the spider in the lifter valley?