Pulling the engine & transmission out of the bottom, with the right equipment/tools and procedural knowhow... 6 to 8 hours with two people. This assumes that you don't run across any rusted-in bolts or any other such road blocks during the process. Someone with a LOT of experience doing this can probably shave a couple of hours off of this. It takes a couple of hours longer putting it back in than it does taking it out. 20 hours is a fair estimate from your guy, and $1700 is a fair price.
While you have the engine & tranny out of the car there are some things that you should have a look at (and probably go ahead and replace), like the clutch & throwout bearing (definitely replace the throwout bearing and buy a VERY GOOD quality one). Also, look closely for any oil and coolant leaks. This would be the time to address any of these kinds of issues.