I had time to work on my engine today. Turns out it's not a 58 model 261 like I thought. The number in the casting date I thought was a 8 is a 3.That means the engine block was cast in late 53, and it is a 54 235.I believe that 54 235s had the "captains bars" cast into the block , like all 261s.That's why I thought it was a 261 ,with the casting date being 1958.Oh well , it runs great and now I won't have to deal with the long to short water pump swap. I'm still going to install it in the 40 and drive it.