hey guys just bought a 306 long block from my friend but number 4 pistons is cracked. they were keith black flat tops. im looking for a new set of pistons any suggestions? im loking for around 10:1 compression to go along with my 58cc windsor heads.

 

I would suggest getting the same ones unless you plan on getting the block machined again....or at least find out some details on your old pistons and try to match up specs on some different ones. Different pistons require different block/bore clearances.