This would be for a "bucket of bolts" not even a good driver was available in 2002 for this kind of money. Try just under $100K as I know of a few that were sold around this time for that kind of money. These were 4.7 liter spyders in nice condition. Ghibli SS Spyders go for significantly more money and as already stated they are difficult to find due to the low volume produced.I passed on a 4.7 Spyder in 2002 at $55k because I felt at the time it was over market value.
Converting to a 5 speed is not so simple on a Ghibli as the frame is different where the transmission is mounted and not an easy changeover with lots of parts involved ie transmission, bell housing, clutch, pressure plate, T/O bearing, clutch slave cylinder, clutch master cylinder, pedal box assembly. There are other small items as well with the cost of the parts alone being very costly. There are virtually no ZF S5-325 parts left as they were all sold several years ago what little remained available at that time. A few synchros are about all that is available and they typically sell for about $250.00 or more each!
The added value of a 5 speed is certainly a reason why one might tackle this conversion however it only takes an email to the factory to verify what the car was delivered with. The conversion is only worth the cost of the parts in the end if that. Original Borg & Beck pressure plates have not been available for more then ten years for the V-8 Maserati and the slave cylinder and other original Girling items are also virtually non-existent.