Bumpers.......What to do

IMO The amount of prep to do either paint or chrome are the same. When taking in the cost of paint; it may be just a little more to chrome them. Also with chroming the shop may prep them.

Will it ruin them to paint and then later chrome; I think not. Later will need sanding or blasting to remove the paint for re chroming.

In order to get paint to stick to the chrome- it is best to remove the chrome, blasting or sanding would work. I know people that have sanded their chrome (on motorcycles) and then painted them and it sticks.