Installed at 1.900-1.920 that's a decent spring for a moderate rate roller cam up to about .660-.670 net lift.
And, at roughly 600lbs open pressure, that's all the spring you want to use with those rockers.

IMO, you don't have the valvetrain components necessary to run any of those big cams you have.

The exhaust ports on those heads are rather small for that sized motor, along with the in/ex ratio not being ideal, so I would lean towards a cam with 10-12 deg split to try and help extend the upper end of the power band.