Are the TTI shorties really my only option?

No, I've never opened up 318 manifolds because there not enough metal to remove to make much difference.

Disappointed to hear that. I was hoping to hog out a 318 manifold, swap that in with a large outlet Magnum passenger side manifold, doing away with the adapter plates and putting $400 in my pocket. :rolleyes:

Oh well.

I do have a plan to square the steering column up to the car which might in the end clear up enough space to put a driver's side Magnum manifold in, but that is so far in the future that it might as well be a pipe dream.