They should work fine on stock heads.

If you bought the complete kit from Crane, it would have come with shafts, 32 .015” thick shims to go on either side of the rocker, and springs to go between the rockers.

Depending on what you use for hold downs, if you used spacers between the rockers instead of the springs....... you could also do away with the .015” shims that go on either side of the rocker.

The .290 offset Crane intake rocker has the pushrod oil feed hole set up in a very odd(and ineffective) way.
With modest solid roller spring loads they would routinely wear out intake adjuster screws.
I would connect the groove in the body to the adjuster feed hole by using a very small burr and making a small channel.
That seemed to be enough to cure it.

I only used those rockers on solid roller cams, so the mod may not be necessary with lesser spring loads.