It's not too hard as long as you have all the right parts, such as JZA70/80 gearbox/clutch, Tailshaft, pedal box to suit? Manuals are quite rare apparently there were only something like 10% made in total production.
I had considered it for about a second, but it's such a good cruiser in auto ! I am just looking for a change in the form of a manual rwd preferably Nissan.