There are more then a few people running that kit but the key is that you run it on completely stock configuration heads.
That was the point of the kit.
Engineering wise it makes absolutely no sense to add an assembly requiring a 7/16" stud and reducing that to 5/16" for convenience sake.
Many people will eventually replace the stock camshaft with a "performance aftermarket one". They generally will require more spring pressure.
Using a 5/16", even super alloy stud, will be a complete disaster.
You won't be able to pick the time or place of the failures but they will eventually begin to snap like tall trees in a tornado.