Nice cars ,Welcome
Yes you can use the 70 type but you need the complete shifter not just the handle , even the later Cordoba / Magnum ball shifters work .
I have witnessed BFG brand new with 3/8" step n the tread , basically out of round causing terrible vibration that has nothing to do with balance
I have seen them last less than 100 miles from brand new with bad belt shift &/or tread separation .
Traction is bad wet or dry
If you lose a tire...
In 70 there was a interlock linkage to teh trans so when the trans was shifted into park it rotates to column & allows the ign cylinder to to rotate back so the key can be removed , without the interlock link the column will need to be rotated by hand to release the key .
Column shifted cars...
It should be running 60-80 lbs , so maybe the gauge is is not going to zero or ti could just be inaccurate everywhere , A mech gauge to test would confirm .
The fuel gauges are rarely accurate but usually show something , does the tank have a good ground , there is a clip to the fuel line from...
Hydrobosst systems are awesome , better assist than vacuum but not cheap .
I bet factory cover would clear the rockers , , the only rockers I had problems with clearance was Isky Solid rockers .
If the Alt is putting out 14 + volts the alt should be working but the battery should read the same so you could have too much load , with electric fans , fuel pump etc . or you could have resistance in th circuit ,corrosion / bad connects etc . The regulator could also be bad , new means...