Chainsaw Repair

Does not have to be new, seems like earlier in this thread a guy mentioned the k650 jug had bigger ports, I really no nothing on these.  used 50mm would be good to, I agree, I am eyeing up that used 48mm, I believe he said that p65 jug was as fast as his 70?  I need to go back & look into what all was said exactly, I prolly got some of it wrong.  Just trying to find out if any of the aftermarket k650 are worth a hoot or not.  Any input is appreciated!