A-833 2.47 1st gear change to 3.09

I'm no expert, but pretty sure you should be able to find an early companion flange 4 speed and swap the gears into your case without problem. Might need to swap the bearings, but I doubt it. And I would guess the side cover swap would require different forks, but nothing else (besides the cover).

The 3.09:1/1:1 gear set is functionally the same or close to the same gear splits as the Passon OD setup and people love those.

Pretty sure the '75 318 4 speed cars used a 3.09:1/1:1 gearset, too. So even the factory went that way.