TOPIC:

I want to switch my '82 KZ750 from handle bars to clip-ons. The bar mount is molded into the top of the triple clamp. If I grind that down, it will leave a big hole. Is there such thing as an aftermarket triple clamp for an older KZ750 (or at least the top plate)? If I just take this to a CNC place to make for me, what type of metal, thickness, etc. should I ask for? Would it be cheaper to just look for a used front fork from a wrecked later sport bike?

I'm not sure about offset and such, 82 GPz750, also known as R1, doesn't have handlebar post on top plate.

Probably the only options are to have a one-off made or swap front ends (not just the forks).
You can check Z1Enterprises.com to see what they have, but I doubt there's anything for a Spectre because of the low production numbers.
The offset Ojisan mentioned would be the problem finding a stock upper triple. 
The GPz triple tree is angled forward to allow room for a larger fuel tank. 
The 750 Spectre triple is kind of straight w less forward offset.

 

Spectre has leading axle forks so it has very little offset in the fork. Likely your only option is a custom clamp. Cognito Moto does custom clamps for very reasonable prices. The other thing to consider is throwing standard clip-ons on a cruiser will result in an awkward riding position. Unless you are raising the seat height and position, and moving the pegs back clip ons will make the bike more awkward to ride.

Another option for a custom triple clamp would be PDM Fabrication, a sponsor of this site.  There should be an advertisement on the bottom of this page.  Contacting PDM would at least give you an idea of what it might cost.

www.facebook.com/PdmCustomFabrication