What is the difference? We've got a 68 that we're building and want to do hidden headlights on it.

The 67s seem better being electric, and cheaper to buy the complete setup.

Advice?

I am leaning toward something like the modern electric kits from Rick's for the 68. The original 67 system requires a specific front light harness to go to the RS relay plate on the fender which a 68 front light harness does not have. 67's have pin connectors where the 68 has blade connectors in the fuse box.
The modern electric kits give a simpler hook up and you don't have to monkey with the relay plate and a custom light harness. I think one of them has a remote control so you can flip the headlights around while you are a few feet away...I know...just toys for the car.:)

What is the difference? We've got a 68 that we're building and want to do hidden headlights on it.

The 67s seem better being electric, and cheaper to buy the complete setup.

Advice?

Can't comment on the vacuum system, but my 67 has the stock electric system, all repop parts because the originals were long gone. The system has worked flawlessly for several years now without the need for any maintenance. I made my own wiring harness, but I think Rick's sells an RS front end kit that comes with everything including the harness for a pretty reasonable price.