[quote=@Dnafein]
But monkeys use their tails like an arm/hand....

The length applied by the leg would be good but then he can't use it right....
[/quote]

Then a hand. But it won't look like a tail on initial transplant. It takes at least a day or two to get the transfer to look like the users original limb. So...you'd just be screwed out of a tail for a while. Sorry buddy.