EQ heads aside (because they are specing them for a certian lift with springs), I think the whole thing with what valve lift you can run comes down to the particular set of heads you have.

Things like valve length, springs, seat grinding, spring pocket cuts can all have an effect. No two heads are going to be identical---unless its in CNC production--even then there is tolerances.

I had a set of stock magnum heads that would take just over .500 lift and another set that was to close for me, i just considered it in coil bind just to be safe.

Safest bet here as in any engine build is measure, measure, and measure.