Using accepted ideas back in '64-'65, I put spring jacks in the front coils of my then-new '64 Custom. I used 'Traction Masters' in the back to control spring wrap-up. Since the car was also my daily driver, I used a 3.50 rear gear on the street and a pair of 8.20X 15 tires.
The speedo went to 120 before the needle disappeared behind the fascia---and then was briefly visible going past the little red window that said 'GEN' although the engine came with an alternator.
Since I only had a 90 day/3000 mile warranty, I pulled the speedo gear out of the trans, but I made a chart of RPMs and taped it to the dash.
The engine had enough 'beans' to pull past 6000 in 4th gear. However, with the front raised by the spring jacks, the front end started to get 'float-y' at about 130. Running against a 'vette one night on the way back from Lansing To the west side of Detroit, I kept my foot in it past 6000. I was steering with just thumb and index finger on each hand, and if the X-way hadn't been straight I'd have been in serious trouble.
By the time I quit the 'vette's headlights were far behind me. I didn't QUITE wet my pants.
And 3rd gear was good to about 125 or so, which was usually enough to settle things.
KS
