Do I need lead substitute?

[eljefino]

I'm surprised your distributor isn't curved for "Regular leaded" eg 89 octane. Of course who knows what happened to this rig over the last 50 years. You might find more power, if you want, fiddling with these things. On the flip side with premium fuel being 33% more expensive, maybe don't.

 

[Gasbuggy]

Just a little tcw3 instead