think it will float the valves at 5k with stock valve train? does the mopar magnum performance springs allow for more lift or it the lift limited by the valve guide height?
I certainly would not take the risk of not swapping springs.
I dont want to pull the heads. I can fab a spring compressor and air up the cylinders to swap the springs, they only cost about a 100 bucks too.
Just use a piece of rope. 18" piece of soft 1/2" rope coiled in the cylinder and bring the piston up to hold the valves. Leave enough hanging out the plug hole so you don't lose the rope.
If its gonna make a huge difference in the engine for less then 400 bucks with a regrind and springs then it maybe worth it to me.