Any info on this tach would be nice

Hello,
I am restoring a '67 merc kiekhaefer 1100ss. I was the told the boat is a '69, so I'm not sure. The boat is a Schuster Tahiti 16' with a bubble deck. Besides the Schuster, I can't find any ID on the boat or trailer so I'm not sure. I pulled the tach and it has no info either. Here are a few pics. I have been looking online and am finding little. I am wanting to see if the tach came with the motor, the boat, a package deal, or something different. If nothing else, I like the way it looks, but I would like it match as well and not over or under rev my motor. Some info would be great.
Thanks
p.s. I have some extra kiekh 1100ss parts as well, so let me know if you need some replacement parts

Re: Any info on this tach would be nice

Thats a early Thunderbolt tach and it's powered by the ign. from the switchbox, It's NLA as they changed the pickup to the alternator with the early system if the tach failed it would kill the engine so todays tachs are all alternator powered.