I have used those pumps in many big blok builds and they work flawlessly, they run about 8 lbs for the most part depending on the spring, some times they hit the block a little and you have to grind the pump housing just a little, but there is no better pump, the clay smith pump is a pos in my opinion i have one you can have for free unused lol. the pump arm on the clay smith flops around and misses the push rod