Looks like I found a completely original ST-70 - the tubes are labeled Dynaco Mullards and all caps appear original. It's a little dirty and the chassis has a small amount of rust.
My question to the group, should I clean it up and leave it alone - save for a simple check up to make sure all is working properly - or start the modification process - new board, etc.
I am leaning toward cleaning it up and leaving it alone and finding another chassis to mod. They can only be original once.