You have duals so whether truck or car, it's not original, so you can do most anything even make it cable operated.
I would concentrate on where the problems is. Do the easy things first.
Throttles not fully returning to rest could mean your spring is not strong enough or is located in the wrong position.
You can add another spring.
You can also add individual return springs on each carburetor.
Before I bought the linkage from mother trucker my stock linkage was getting hung up about half throttle on the exhaust manifold
I also thought my spring wasn’t returning it back to the idle position
