I fitted your rockers with the standard GM bolts and was wondering if this will make any difference if I didn't fit the ones you supplied me with?

It is recommended that the rockers are fitted with the bolts supplied. In saying this though, if the factory rockers weren't stretched when they were removed and have sufficient factory thread locker left of the bolts then they should be ok. Worse case, you may have to re-tighten them after a couple of hundred kilometers