rebuild yes. Turbo no.
Oaks are a rare car as they are, and are increasing in value. Turboing involves a lot of internal engine work, and will cost a good few grand to do. An engine rebuild can give it back the poke it had and gives peace of mind that nothing is going to go bang on them and cause a load of damage as easily as on a turbo. (although this is not a 100% guarentee as all engines can blow)