Good job on the decoding.
The location of the water pump and fan is different. And, the 1958 fan will be too close to the radiator.
Pre '68 Dave makes a relocation plate. You use the original style water pump; and, the plate places the old style pump in the correct location on the new style block.
This provides better cooling and you do not have to fool around with getting a short shaft water pump (or shortening the shaft on the water pump),
Your solution to the front mount is correct.
