Howards Cams lists a "pro" series endurance valve spring that looks right in line w/ the specs I think would work w/ a cam I have in mind. Does anyone have any experience w/ their spring products?

They actually offer the same spring in standard and an electro-polished version for a bit more $$$, FWIW.

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Oh, look... a rolley cam.

I asked this question on the drag race section over at the Yellow Bullet Forum Brad... The constituents said they are a good spring, and those guys dont mess around with junk.
Ultimately I went with a set of Pacaloy springs and matching Titanium retainers for the new engine though. Part number 1224 which was a 1.625 diameter spring with a 1.95+ installed height and can accommodate a .800 lift cam.
Same springs I ran on the wedge for several seasons...So I stuck with what i knew worked well.

That's encouraging. What Howards has is a 1.55 OD dual (no damper) that specs at 230 @ 1.88 and 550 @ 1.25". This is basically "nuts on" for what I think the cam pictured above will need for spring loads, given the need to stay in control through 7200 rpm (expected trap RPM).

The other choice is something like a Comp 943 (or the Trick Flow or PAC equivalent) that's 250 @ 1.88 and 600 @ 1.25. I think that's more open pressure than necessary for a .600"-ish street roller, although I'm expressing an opinion, not a fact.