349 CI on the cheap

my question is....
i read its got a 3.51" crank stroke? now..
how do 318" pistons clear that stroke? the counter weights will interfere
with the pad material below the pin location...and hit the crank?
yrs back i wanted to put pop up 340 pistons into a 360 block and crank..
and the counter weights hit teh piston....?

cheapst.