All in all, the manifolds were WAY more easygoing on this project than I expected.
I expected a lot of seized bolts, instead I found everything finger-tight. Even when there was studs they were loose in the head AND on the nut. The rearmost one to the firewall was even completely missing. I replaced both with bolts and their special washers salvaged from another Eagle.
Though to be honest, torquing them was not as fun. It wanted 26 foot pounds each and you could only get to them with a socket U-joint, so I put them all in at 15 and we'll see how that lasts.
The EGR tube on the last eagle I salvaged from was seized on pretty tight and had to be cut off. This one, again was easy to crack the threads on.
Bolts on the electric heater? No problem! Even the EGR was fine.
I did however notice that I was missing an exhaust manifold gasket. I assumed that this was someone previous neglecting to install it but no, that was normal. The gasket kit I ordered made sure to note that while one is included with the kit, finding manifolds without an existing gasket is perfectly normal. Man with how loose everything was this probably explains why this car ticked like a sewing machine so much.