over size valves

I'm woundering if amy one knows of a valve with a larger head dimator and 3/8 steam That we could use to bring the seat back in a set of other wise good set of large port heads could cut down the steam length and put new keeper groves if needed
Thanks Flatrat Richard

can't you renew your seats?anyway,this maybe helps you,the V-TWIN cataloque mentions a knuckle stock replacement valve,nitrate finish,1/8''oversize,i assume this is for the valvehead,its not mentioned.(V.T.no.11-9642)(OEM18071-36) goodluck