[jluetjen]

I don't think that there were ever factory weber manifolds for 2.4 engines since they all came with injection of some sort or another.

I believe that there were two flavors of manifolds pre-69; as you described the large bore model for S's and the smaller bore model for the other models. I believe that PMO also makes manifolds in both flavors. It sounds like you have an S manifold which is a cool thing to have since it doesn't need porting to match the 36 mm ports of S's and other modified engines. It saves the trouble of having to port out the 32 mm T manifolds. That being said, I believe that the time and effort of porting them is the only change. So they most likely aren't worth any more then a standard T manifold + the porting cost.

BTW - I wouldn't use them in your engine unless the heads have been ported out to 36 mm's to match. Having the step down in size on the intake would be an evil thing.