I suppose that if you had everything you needed and have done it a few times before, a conversion could be done in a few days. There was a write upon this forum a while back where a couple of guys did one in a weekend. Probably not a pretty job, but they got it rolling.
A lot of time goes into the detail work, and learning how things fit together. I went to the pick-a-part yard several times just to dismantle various parts of their cars so I wouldn't screw up mine.
The kit does not include an exhaust system or a driveshaft, those will have to be fabricated. Modifications need to be done to the radiator. Snaking the wiring around, figuring the placement of the smog components (I'm in CA), re-routing the brake and fuel lines all takes time.
Worth every minute!
TR Conn