Are these things as rare and valuable as people are saying?
I was about to hack mine up, but now I am wondering if i should try and find something different to work.
I am not running stock gauges, so I was going to cut the unicorn off and drill 2 holes for mounting points
I did just what you suggest back in 1976 or so. Cut the point off leaving two spots to drill and tap. Attached the 2 halfs of a hose clamp and mounted a tach right in the center for my racebike.
However, times have changed. Sometimes those go for $100 or so on ebay. But on the right week I've seen $270 for a used one. There's a "Buy it Now" one for $280 right now. He'll probably get it if he waits.
One by one, as these are broken and buyers come along to restore old CB750s, I'll bet we see the day they are $500+.
Sell it and use the money for someting else and keep an old bike on the road for someone else. Those things are unavailable and really not repairable. Though in truth i am a capitalist, it is your part do with as you like.
And just to avoid an avoidable tragedy, you do know why they break? There is a spacer that goes in the gap of the clamp on each side. If you tighten down tha clamp without that spacer, it will break. Then you end up on the demand side of the equation rather than the supply side. Do you have those spacers?
You could sell it and buy a later model bridge to modify for your project. They go for $25 to $50.