that is good advice-particularly if one is using an aftermarket cam. I would suspect a lot of machinists may not be familiar with these engines and turbo cars in general so I would tend to start with what the cam manufacturer suggests.
In this case, we know what we are dealing with so the comp 980's, or the equivalent, is the tried and true spring that will allow the engine to rev to 5300, or a bit more, without undue wear on the lobes and they should provide a bit longer life.
It is seldom mentioned, but Brad just did above, boost in the intake will try to hold the valve open when it should be closing and if one figures the psi on the back of the valve, this can really make an old set of springs struggle which is the reason we see engines go flat on power in the lower 4000 rpm bands so often
