As long as the hull is sound and in good shape, then there is no bad restore really as long as your willing to put the money in and keep the boat a while, you will likely never get anywhere near the value of what you put in when you sell so do not use that as reasoning ever to upgrade, do it because your keeping the boat and feel it is necessary. As stated above, a repower for an I/O is fairly cheap so be realistic as to what is worth fixing, at some point it might be cheaper to upgrade to a newer engine that will do better on fuel and be new with less issues, if the fixes are something smaller, then fix her up and get her running. Make sure the transom itself is sound, ideally you need a surveyor or a yard to check it, you cannot inspect it yourself and every know, if there is any transom issues, then it might not be worth the money since a cheap transom job will run you about $2000, and could be more if it runs into the stringers or bulkheads. It sounds like she is in good shape from what you state, and likely is, but there can be things you might not see as far as transom and bulkhead issues that would not make it an economical investment, if those things pass though you should have a great project boat on your hands. Best of luck, hope it all checks out for you!!