Spark Plugs and Seat Belts

[gmc396]

I recently bought a 1968 GMC 2500 with a 396/4-speed. I see the original AC 43N spark plugs are no longer available; what do you recommend for replacements? Also, any suggestion for manufacturer for points and condensor?

The truck has lap belts, and I would like to add shoulder belts. Not sure if this was an option in 1968. I see the hole in the pillar where the belt would tie down, but I want to be sure that the shoulder belt would be secure in the event of an accident. Can anyone suggest a place to buy the belts?

Thanks; glad to be part of the forum.