you want the rockers to track over the center line of the valve stems if off then you can slot the guild plates if off one way so times there is some movement .you did not say how big of a cc intake runner is in the head. the bigger runner some times throws the pushrod off .as the port gets bigger the intake push rod would break thru the port s so they move it and the rocker will be at a angle push rod guide needs to be ajustable.as well as moving the plate up or down can help when using guid plates the heads need to have the heads drilled out if stock heads.and spot face if as well. make sure your not hitting in side the heads push rod holes .if roller rockers you can be off a small bit as long as you do not track off the valve stem. you need a push rod made for guide plates . you want to move guide till they fit the best on the engine with push rods in it set rocker arms on so they can be checked and moved till the rockers fit the best then TQ the studs down .reworking guid plates is nothing new it has to be done from time to time