Master parts book shows that dist. was for '55-'57 Chev all 6 cyl 12 volts. Is that the dist. that was in there when you got the truck?

I do believe the '54 drive gear on the cam is steel but the '55-'57 dizzys used a cast iron gear and you can't mix and match them.

Hopefully someone with more detailed info will chime in soon but I wouldn't run the engine too long until you know for sure.