swapping early 3.09 1st into later case

I understand your point. Quite a while back I owned a '68 Fb 340 formula s barracuda with 3.07 rear and the 2.66 trans. The cam was not or low end torque, but it was workable. I have talked to the tech's at Hughes and Comp Cam about what I am planning on doing and both told me basically the same thing, custom ground cam for the 340 combo I have planned due to need for low speed torque. The '67 Fb barracuda I have is going to be more about handling, drivability and road trips.
That is why I build a 367 with a 4.04 bore. She's my stroked 340. Those cubes come in very handy at low speed. And I had the same idea as to the end use, back in 99 when my 68 S-clone hit the road,namely; handling, driveability and road trips.
Good luck on your combo!