Are you saying that if someone wants to buy your board you can include an extra 68030 chip, or are you saying that you would like someone to replace the chip for your use?
If the latter, I'd recommend leaving it alone as long as it is functional. I could do the replacement (if I could ever find the top of my desk), but there's always some non-zero chance of failure in such a replacement--not to mention uncertainty as to whether a new component actually is a functional component. The bad possibilities may have a low probability, but there are risks.