You can actually get it done in 3 days. However, you'll have to get Chip Foose's crew at Overhaulin' to do it and it'll be done in a snap, especially if you have Courtney Hansen helping you.
Seriously, as someone who has had the drivetrain in and out of the car several times (I once was able to take my SBC/T56 from the garage floor and bolt it into the car in 45 minutes!) I can tell you there are other issues that will hold you up, such as wiring (keep as much of the original engine harness as you can), exhaust (have someone else fabricate it--trust me), cooling (fan, radiator) that will draw this project out.
In order to make this the most time efficient, I would make sure you have all your parts lined up and stick to a checklist. In other words, exactly the opposite of what I did.
Also, I wasn't sure, but is the rest of your car optimized? I hate to see brakes cry under the strain of double the horsepower they were designed to handle. I'm a fan of brakes/suspension first, then engine.