Re: 221 rods into 250
The compression ratio will go up cos the piston will be popping out the deck and hitting the head.
ACL make 2 sets of pistons for the 200 rod onto the 250 crank. One set they say need to have the top of the rod modified so it doesn't hit the innner side of the piston.
Someone had a set of Probe pistons for sale here. Sure he is in Townsville QLD.