I think the 79 has a cast crank while the 73 has a forged crank, I also think exhaust manifolds are the same. Send a PM to slant six dan, he can tell you EXACTLY what's different...probably right down to the part #
I believe ssd is on a sabatical from the internet haven't seen him around in months.
I would likely just swap the fire damaged parts out with non damaged parts. How much fire are we talking here? Was it enough to warp the hood? A slant is almost entirely cast iron and it takes quite a bit of heat to hurt it.
I believe the heads are different (peanut vs drool), but do interchange. The intake and exhaust manifolds do interchange. The 79 head might have the air injection port (easy to block off). Yes a 73 should be forged and 79 should be cast.
