420 hp 454 motor has 500 hrs and was woundering what the cost should be to have rebuildt runs great but want to paint blige over winter and thought it would be a good time to freshen up

That would be a hard question to answer. Are you going to do the work yourself or have a shop do it? If a shop does it are you just going to give them a blank check and tell them to do what THEY think needs to be done? There's just no way to give you an answer without knowing just how much would need to be done. Complete rebuild I would say 2K+.You say it runs great. Personally I would leave it as is. Those engines with proper maintanance will run twice that many hours or more. Maybe clean it up and touch up the paint.

what he said....if it aint broke.....