Yeah a t56 swap is fairly common. You will probably need a different trans mount as well as the bellhousing. You can get t56s as low as like $1800 from D&D I think.
i have a d+d viper t56 i killed my aod and did the swap grand total was 3650 the tranny is great i dont know if i will be able to come close to the power rating though up to 1000 hp d+d claims i did slam it into 2nd grear going about 90mph and didnt hurt a thing on accident of course tried to go from 6th in to 4th bu missed if i could do it over i would get a tko 2 btw at 80mph the rpms are at 2000 with 373 thats cool i guess