63 Dodge Dart, now let me see;)

I see you have the trans installed, is the trans mount bolted into the crossmember? if it is the distributor looks like it might clear the firewall.
Exhaust manifolds from a 5.2-5.9 magnum truck should work if you keep the manual steering but you might have to change the coupler from the steering box to the shaft.
I'm doing the same swap 5.9 into a 64 dart, I'm waiting on parts from Borgeson to make my steering column collapsible for safety concerns if in a front-end collision. I'm using the magnum truck manifolds, looks like they will work just close in some areas.