here is a graph for the 172 f4r engine - valver and willy very similar.
this is G force against rpm.
the gforce is the force experienced by the piston, wrist pin and the crank pin..
these are HUGE loads.
between 1000 and 5000 rpm you have a fairly linear increase in load.. between 5000 and 7400 you double that .. AGH!!.. go above that.. and all I say is I hope you have some pretty bloody strong fasteners, pistons, crank etc..
Have fun.. and maybe reconsider if you want the rev limit upping..