>Or install the shift linkage rod after the tank is
>already in?  Or use flare fittings so a metal line
>could be attached to metal fittings?

>etc.

FWIW, on my '64 Corvair van and pickup, with similar layout of components
including fuel tank in the same location, the shift linkage is routed
through a tube, about 3" diameter, right through the tank.

This was the improved design after the earlier models experienced problems
with the linkage routed under the tank.

Vern