Valves.

Are there aftermarket valves available which are one-piece, stainless steel or
titanium or some such substance such that the head doesn't break off and drop
into the cylinders when they get fatigued?  I understand that there are
warning signs before this usually happens (burned valves = low compression,
etc), but preventing it altogether during a rebuild seems to make sense if
there are some kind of cool valves available out there somewhere for a
reasonable price. This would be for an '82 air-cooled 2.0L....

Gary ('82 vanagon L with engine that sounds like chipper/shredder)