for that much you could build a sweet auto that could have the potential to put a fair bit of power to the groud.
i never used to like autos, but driving some cars at work and mates cars, no i dont mind them. (still prefer manual tho)
get the trans rebuilt with better and more clutch packs
up the line pressure
get a convertor with decent stall 2300-3000 rpm
oil cooler
then see how it goes. i bet you see a vast improvement in take off and speed, would be cheaper than the manual conversion by the sounds too...just my thoughts