Both are v8s 560 is 5.6l and 380 is 3.8l. 560 hands down better engine. the sec never came with 6 cyl in usa
early 380s had single roller timing chain and pulled threads from block they also have a hesitaion right off idle they can fall flat then pick up very common
560 will have better resale
look in some of the dryer states nevada, arizona and california