I was reading the specs of stock heads 906 They have the 2.08" intake valves and 1.74" exhaust valves and
915 are 1.60" on the standard head 2.08 intake

The heads on my engine are 2.14 and 1.81.. does that mean the heads have been ported already? sorry if its a dumb question just curious.

 

Sitting on my but in north Iowa I can't tell what's been done to your heads, but I would not put the bigger valves in without at least pocket porting them. Look for evidence of port matching in the intake and exhaust ports, you should be able to see the back side of the exhaust valves and ports easily.