A body Exhaust manifolds

I'll be installing a 340 with X heads as well as an 833 4 speed replacing the 273 HiPo [that somewhere along the line someone replaced the 10.25 pistons with 8.5 slugs] into my '65 Dodge Dart original 273/904 car.
I bought a pair of Doug's Headers but now I have learned through this thread that the conversion 10.5" clutch and bellhousing (from Brewers) will not fit with the mechanical linkage and Doug's headers. Has anyone successfuly used the 340 original exhaust manifolds with the 340 10.5" bellhousing and mechanical clutch? Do I need to buy a 9.5" bellhousing and clutch and go with the Dougs, or stay with the 10.5" clutch and 340 cast iron manifold?
I can remember that I had clutch/ bent throughout arms with my original 273 HiPo Dart back in the day, but modern clutches are much superior to the original Mopars.
This whole thing is getting way more complicated than I ever imagined when I started down this path....