Hey Anthony, Many feel that the key in determining if a cylinder scratch will generate a potential sealing problem is if you can feel it as you pass your fingernail over it. Even if the proper corrective light hone and a set of new rings gets your project back up on it’s feet initially, in the long run you will regret not resolving this cylinder issue. This can be especially true if you intend to own and enjoy her for a long time.
Although the machine work needed to restore a Nikasil cylinder is usually the best route, once the damaged cylinder is factory fresh, sometimes finding a practical stopping point in deciding how much should be done to the remainder of the block can be difficult. Often a reasonable compromise (and least expensive option in the long run) is to locate a used block in good condition or even a complete newer engine. This can be especially true if parts availability for your 4.5 liter original motor is a factor. When cared for, there are many 928 engines that push 200K miles and still have lots of service left in them.
Good Luck, Michael
