1950 3100 with TH350. Fit the cover plate. Mounted a lokar cable shifter to cover. Now need to fasten cover to floor. Holes in floor were welded shut when floor replaced. I need to drill new holes and contemplating:

1. Thru holes with bolts on backside. This would be tough because of the large flange on backside and potentially nuts not fitting. Plus the hassle of having to put nuts on backside from under.

2. Tapped holes? What size? I’m thinking 1/4—20

3. Sheet metal screws. May not be rigid / strong enough for shifter?

Other ideas or feedback?