have a 402 in a 72 gmc truck. cyl 8 and 5 have 30lbs. since I want to sell this truck after painting and interior is done, can I do a ring kit only? do I have to pull motor or can drop pan and pull heads? I would fully disclose what has or not been done to motor but would like it to run decent to sell. if not can sell as a mechanics special. any other recommendations for engine repair welcome.