Once you have gone solid, you won't go back.You will need differant pushrods(make sure your springs are ok with the 557,(which by the way rocks IMO).Setting lash is no big drama and contrary to popular old wives tales need not be done all that often,... as long as no valvetrain problems are present to start with.Setting lash cold is fine,pull the valve covers and set up 1 cylinder at a time.Lash is over-rated and although you should follow the manufacturers specs, the engine only really cares to see some clearance at operating temperature.There is a voice in your head saying...go solid...go solid