94-98 3.8 to 99 body

hi all, i'm new to the forum and haven't had any luck in searching for threads that would help me with my issue. i bought a 99 roller from a buddy from work with the intent of dropping a 333 stroker in it, but time and money constraints have made it to where i need to get the car running now and want to just drop another v-6 into it. i have most of the parts off the old motor, but the block and pistons are rusted together so there is no real point to rebuilding the motor. i can't find any 99-04 v-6's where i'm at but there are loads of 94-98 3.8's around. how hard would it be to swap this motor in and what mods would i have to do to make it work? any help would be much appreciated.