I just had the '88 cyl head /cyl modified by Jerry. He can machine out imperfections up to a point then your head becomes a conversation piece. It's not cheap as the coolant passages are reduced on the exhaust side, squish /dome modified, sealing surface milled flat, oring lands machined in. It came with orings. Expect to spend two Benjamin's 

Yes its money well spent and a critical mod/upgrade for the 500's. Send it to Jerry............