So we're talking about a good old fashioned gyro going on an older bike? So it has no tabs or owt like that?
Its very long winded to explain, but initially you need to assemble it in this order;
1. Fit lower gyro plate onto headtube.
2. Fit upper headset cup into headtube. This secures the gyro plate.
3. Refit the forks.
4. Assemble and fit the upper headset stuff, apart from the top locknut.
5. Drop the gyro bearing over the lot so its sitting on top of the lower gyro plate.
6. Fit the upper gyro plate. Secure in place with the headset locknut.
That should take care of all your gyro bits and bobs bar the cables.
Now, cables......
1. fit lower cable. Be sure that when everything is done up and the brake caliper is just off the rim nicely, the gyro bearing should be being pulled down tight against the lower gyro plate. Very important, this bit.
2. Fit the upper cable. Try to make as few a adjustments as possible on the upper cable, as it can interfere with the brake performance.
Finally is setup;
First of all, by adjusting the upper and lower gyro cable adjusters where they go into their plates, you want to get the largest possible gap between the gyro bearing and the upper gyro plate. Usually, this means lower cable adjusted all the way down, and upper cable adjusted all the way up. Take out any looseness in the lever with the lever adjuster and/or the upper cable barrel adjuster in the 2 into 1 peice.
All actual brake adjustments should be made with the adjuster closest to the brake caliper itself. Do this last.
That should be it. I'm sure I've forgotten summat, but this should get you going
