probably about 20,000 or so at the spark plug boot..
Where exactly was the damage? If the handle bars got banged up the trouble could be the kill-switch or maybe it's wiring.
To check for spark while eliminating all harness wiring and switches, connect the Black condenser wire (condenser is mounted back near the HT coil on the right side swingarm) directly to the Black/white stripe wire coming from the magneto.
These connectors are all in the rubber boot thing near the petcock.
The engine should then run unless the fault is elsewhere ..
While you're in that rubber boot, double check and see that all those connectors are still connected.. on an old bike like this the connectors can be loose..
"THIS":https://www.mopedarmy.com/forums/discuss/download.php?f=6&file=1082480832_honda_pa50_1978_wiring_diagram.jpg is the wiring diagram for the '78.
Otherwise the plug itself may have been hit and cracked? (Try a known-good spark plug of any kind) Or the spark plug wire was twisted and is broken?
It would take a hell of a shock to disturb something in the magneto..
if the bike starts and runs with the above condenser-magneto wire test, you won't be able to shut the engine off with the key or kill switch.. So disconnect those wires or pull the spark plug lead off the plug with insulated pliers to kill it..