What car to keep?

Ok I have these two cars and need to get rid of one. A 1984 mercury capri AOD auto trans with a 351 windsor. The other car is a 1982 mustang GT with no motor but 5 speed manual. The motor needs to come out so I can fix the oil pan leak that it has. Should I put the motor in the mustang and sell the capri. Or keep the capri and sell the mustang?