Just came back from machine shop.1976 350 sbo ,He showed me that someone rounded off were the main caps sit just enough that he doesn't want to guarantee the work could I use a griddle to stop the main caps from walking and studs

 

Not sure what part exactly is rounded off ??? How about a picture ?

 

Right were the main caps sit on the saddle were the bolts screw in the edges are kinda rounded off he saying that the caps will move and it will give improper thrust clearance

 

Sometimes you can peen those over to make them tighter. However the thrust isn’t the only thing effected. If any or all are loose then the overall alignment will be compromised. If you use studs that will help in keeping them located where they need to be but it still depends on how loose they are to begin with.