'68 Barracuda Formula S Fastback Restoration Background

Ron,
This is exactly what my car looked like 55 years ago. Cragars and all. Except for the Formula S emblem. Mine had the Finned hood inserts and not the 340-S inserts. I think that was do to front end damage before I got the car. A few hidden issues showed up during restoration indicating that the front end was hit very hard. Bent right frame rail that was straightened and welded, front radiator core support that was brazed in place but the wrong place by 5/8", and the aforementioned hood inserts that are from a '67, not a '68. But most of this has been corrected except the core support which we didn't figure out until the fan wouldn't fit with the new longer water pump. The '70+ WP is 3/4" longer and was needed to fit the Edelbrock Aluminum heads
I run Edelbrock heads with the early cast iron water pump along with the '69 and earlier water pump and crank pulleys. Not understanding why you had to go with a '70 up water pump?