Metal, like all materials has a matrix the matrix of most materials is decided at the time it is made. It has to do with gravity, tempature and electromagnetic influences nobody can fully predict.
This is in part why Ford went to high nickle content alloy for it's side oilers. The process involves freezing at very low temperatures with liquid nitrogen. The process realigns the matrix of all metals into a more stable pattern. Zero gravity has a similar effect on materials... The result is generally a 200% greater life for machine parts, tools, engine parts. Strength is also increased.
However... Therein lies the rub. If a treatmment costs $2000 and a block will last 150k miles between borings is it wort it? As for valvetrain, I'm sceptical a cryo treatment will yield enough benefit to justify the cost. Most street engines are far more durable and far stronger than needed with a good quality
synthetic and regular service.
Get a quote, don't forget prep (total 100% disassembly) and shipping. Maybe it's worth it, maybe it isn't.
I know several snipers who have cryo'd their M40 barrels with great gains in accuracy. This process was about $500. for a single rifle barrel. Cheap considering it puts enemy mortar's out of reach.