call each company and ask what there seat pressure is on the spring and what there over the nose spring pressure is. generally you want to go with a VERY high pressure spring. all of our race engines run PAC dual valve springs with 230lbs of seat pressure. just make sure your cam can keep up with it and is heat treated right otherwise you'll wipe out lobes.

a higher spring pressure will result in less valve float in higher RPMS. but you may have to change out springs more often.

you can raise your spring pressure using a regular aftermarket set (such as skunk2) by using shims but i don't recommend it. they generally can't with stand the added pressure for long.

BTW i'm using Supertech's lol.