That may work fine. It depends on which type 4th gear Pr
. switch is on the Valvebody, 1-Pin or 2-Pin and 1-wire or 2-wire TCC Solenoid.
You may not need the -Ground wire, only 12V+ to Pin-A.
This will help you understand what I'm talking about
With the Toggle switch you can wire it to Lockup in 2nd, 3rd & 4th gear or 4th only. With a permanent -Ground connected to the Solenoid flipping the Toggle switch would lockup when ever you wanted 2nd, 3rd &/or 4th.