Newby needs help

Hey guys I just bought my first mopar 73 dart sport slant 6 but got a motorhome 440 and Trans with it I dont think I want to use the big block cause this car is a father daughter project so I was wondering what I could get outta selling the bb and what size motor I should look for to build a decent daily driver any input would be nice I always been a foxbody mustang guy until my girl fell in love with this car