Similar paths...
Seven years ago I purchased a 1962 Impala that was ordered from the factory with a 283 and a powerglide. I drove her like that for about three years before I took her a part and slipped a dual quad 409 with a four speed behind that. Also put in a posi rearend. The difference is, well, unbelievable
. But you might expect that!
The swap was very easy, the engine perches are the same, the trans lines up easily, the drive shaft will need to be modified slightly. It wasn't too hard to open the floor in the correct location for the four speed shifter. I did have an extra problem in that I went from one brake pedal to the brake/clutch setup, but you won't have that issue since you already have the 3 speed. I went to the smooth column look (you can shave that nub off easily and repaint your column if you'd like) for the four speed.
Several of us have done this, and there's even a "sticky" with instructions for converting to a four speed that you will find handy.
The hard part is finding and building your drive train. I located a correct 1962 Borg Warner T-10, but went with a scattershield just in case things shattered under duress
. Do you already have some of the parts, such as the 409? There are several discussions and posts on building a "budget 409" but the costs associated are not the same as the more common SBC.
Ask lots of questions, tell us what you are trying to accomplish and we can give you advise, then you get to fund the decisions!
BTW, I live in Columbia, less than 150 miles away. If you want to feel what it's like to be in a 409 four speed, look me up!
Cheers,
TomK
Great group of guys ! 
Lots of pics of your ride please and any projects.
bang You have a dream and now some idea's to form a plan (They always change during a build
) I kind of like the 3 on the tree idea just because it's different. Just don't know if the Saganaw will hold up to a beefed up 09
just somthing to think about. ken