Is the camshaft gear's timing mark in the same place on both engines? I think the crank gear mark is different between the two. I have never looked to be certain.
Yes. The timing mark is in the same place on both engines, plus, it's in the same place on both style big block camshaft gears, the center bolt and three bolt. The crankshaft gear and timing chain are the same. The camshaft gear between the slant and big block is where the difference is. The slant six camshaft gear has more offset to the front. This is the reason for turning the crankshaft gear around. The big block camshaft gear sits closer to the block than the slant six gear would. Chrysler could have saved some money here, had they simply machined the camshaft gear for both engines the same. They could have used the same timing set.
Edit: ....and even if the crankshaft gear mark is different, it's a moot point, because I am going to remark it anyway, since I flipped it over.