The edelbrock e-tec 'vortec' heads are set up for both bolt pattern valve covers, and complete (valves, springs, guide plates) for $1000 can handle cams up to .600 lift!

and being aluminum, they are pretty.

The vortec style valve covers are not cheap. they seal better i hear, but the cost...and you have to run stmped steel or 'special' alum rockers to clear the bolts.