You have quite a loaded question there, seeing that it would depend...
If you have an exact Idea of how you want the ride set up.
ie.. Brakes, rear end, tranny, motor, suspension, ect.
If you have all of your parts bought and sitting waiting to bolt on, and have deep pockets for those items you didn't plan on. ie..
If you have a vehicle that needs minor paint and or body work.
If Dave Gordon, (Flash68) jumps in and takes over the lift.
Given those parameters.. 1 - 4 yrs.