For 350Kws just get the standard auto box rebuilt as standard they are good for around 200 to 250kws. You will need to run the box with a full manual valve body as you are running a PFC and they dont control the auto box (so it wouldn't change gears properly). You will then need to get a good high stall converter if you want to drag, but bear in mind you will be driving every day so dont get too greedy.
You can pick up the standard auto box for around $300 or so and you will need a new transmission crossmember, tailshaft, transmission cooler (dont skimp on this), pedal box, dash cluster, centre console, gear changer and linkages, and I am sure I have missed somthing else here, but thats all I can think of at the moment. You are doing it the cheaper way (opposed to changing auto to manual) so the cost wont be huge, I reckon you could get all the bits and peices for under $1000 and then the cost of the auto rebuild ontop of that (I have no Idea in the cost of that) and installation.
Best of luck and I am sure that once you have this done you will see faster 1/4 mile times.
I hope that helps.
Chris