Good advice so far. I second the comments to make sure you have a good cooling system. 30-40 PSI oil pressure at idle at 180 degrees will be under 20psi at 200+. As far as lash I didn't see then changing with good rockers. I checked them a bunch at first and they never changed. I made 800 HP with a 557" motor on pump gas, it was around 850 on race gas with more compression and a bigger cam but I turned a little more than 6800. Lot's of years ago but I recall peak HP was around 7500.