Vortec head questions

[pushrodv8srule]

I have a set of low milage vortec heads that i planed on using for a mild build up. I was looking at the chamber side and am wondering if having the machine shop do a "chamber sweep" cut to unshroud the valves alittle would be an easy/ cheap way to improve flow, since they will already be in there doing a valve job. Also do you think using exhaust valves with the undercut or necked down stem area is worth the 80$ price / gain in performance. I've been told vortec heads flow alittle weak on the exhaust side.
My goal is a 450hp 400sbc using pump gas, and of course, a tight budget. Are these heads capable?

[olds48]

They are perfectly capable of 450 hp.Without ant additional headwork,except probably cutting down valve guide for retainer clearance.They were pretty tight in stock setup.And have small spring pockets.But they will work for what you want to do just fine