Edit: Looks like heads are coming down in price like carbs and pressure washer pumps....GOOD!!And never, never ever ever, buy a new head. You're ending up with the same junk that failed you in the first place.
You really never need to replace a head unless you find one with an extensive crack. If you have one that has to be replaced and simply get a used one off of another engine from eBay or swing by a local small engine shop and buy one out of their junk parts. Popped out valve c or slipped valve guide is an easy fix that cost zero money. A new head is like $150 plus. You would be better off to take your head to a machine shop and let them fix things which would result in a better quality head than a brand new one.
Still, they are not new and improved. Briggs hardly ever does that. Kohler on the other hand had a head gasket blowing issue on the twin command they put out a kit albeit overpriced that FIXED the problem. GREATLY improved head gasket and new bolts/studs.
Briggs still give us the same old lousy single ohv blowing out head gasket that failed the first time...or 2nd.
I will put my cleaned, grooved, and loctited repaired head up against any new one in a overheat challenge to see which guide will slip first.
We could heat them in an oven and have a press with scale on the guide and see at what temp and pressure one moves then the other.