904 or 727

i need to get a trans built for my car but im not sure what way to go. I would like to stick with a 904 because it will use less power to turn but the cost is going to be higher also how much power can a 904 hold??? Or i can save money and build a 727 but loose power.

BTW: i have a small block with a procharger running about 550-600 hp.