Valve spring options

Conical springs generally have a higher rate than beehives & take more lift.
The beehives can run 10-20% less spring rate than conventional springs because of the reduction in weight that the springs need to control.
I would use the Comp 26986 beehives [ or equivalent ]. Designed for hyd & sol flat tappet cams, 280 spring rate, 650 lift, for small blocks.