[blykins]

This is going to be a love-hate relationship as you need adequate spring pressure to keep the valves in the right spot at rpm, but that cast core cam isn't going to like the pressures that you're going to need. It will start flaking.

For a 1.900" install height on a Victor Jr head, I would at the very least run a Comp 954 spring (and probably shim them up .030"). However, the 991 spring would be one that I would towards using for an engine pushing that kind of rpm with a solid roller.

The whole system really needs to be critiqued to make reliable power at this kind of rpm.