Nothing marking wise on the TC or flexplate. The TC i ordered vs what i posted are vastly different. Mainly the setup that uses the square shank nuts. Im trying to find more info on the TC specifically to track down an actual comparison.

 

The torque converters for a cast iron power-glide are not the same as those for an aluminum power-glide. Check to make sure you have a torque converter for the proper transmission.

 

interestingly enough, I was looking for something else just now and came across this parts catalog

https://www.wittrans.com/catalogs/witcatauto.pdf

take a look at pg 176-182 where it references part #s for Aluminum powerglides
on pg # 183-184 it lists parts for Cast Iron powerglides

 

Not sure if this helps, but if that is the first time the tranny has been out in a while, you should inspect the flex plate carefully. The plate may have some significant wear on the teeth, so it might just be easier to get a new flex plate that matches the TC. Can you seen any part numbers on the plate or the TC?
Nice ride, BTW!