Spring/Keeper interference with Rocker

Alright guys -

I installed new exhaust manifold gaskets - still ticking.

Went through once again, checking for any play in rockers after getting it up to temp, no play. All lifters are staying primed.

how much pre-load should there be on these lifters? Should I be able to spin the pushrods if the valves are closed?

I'm thinking about swapping rocker sets from one side of the motor to the other as a test, do you guys see any issues with that? Trying to isolate rockers from springs/lifters.

Thanks again.