New Cam break in

It's the best insurance to do it that way. I've even put worn OEM springs on in place of heavier single springs for break-in. Changing springs is a lot less work than changing the engine if the long-shot gamble doesn't pay off.

Comp Cams, Mancini and others sell a nice little tool that bolts on to a pair of rocker stands to remove 2 springs. Then just move it over to the next 2 stands.

Compressed air or a firm rope with the piston rotated towards compression works well to keep the valves closed during the swap.