all relief springs are interchangeable. the problem with the hv pump is the high pressure relief spring. the factory had 3 relief springs during the '60's. the red stock 45psi spring, black 65psi street hemi, and plain 75psi race hemi spring (rare to find). the hv spring is a 75+psi spring and is totally unnecessary unless your building a bottom end bleeder. I don't think the black street hemi spring is made anymore. anyhow, my engine with the hv pump and stock spring runs 55-60psi hot on the road and I don't use heavy oils or excessive bearing clearances. hot idle in gear 38-40psi. I feel very comfortable with these pressures. excessive pressures will eat up the intermediate shaft and bushing. I chose this combo because I wanted a little more low rpm pressure/volume without the downfalls of excessive road use pressures. the nice thing is that all this can be played with by just unscrewing the relief cap and changing springs or shims.