Overhauling is a good way to go but it depends who is doing it. after you get the new things installed you need to crank up every bolt to a specific power to get the correct factory figures of compression and all. otherwise things jhatka mechanics just put all their power on the bolts which is not right. what i mean to say is that OVerhauling is a better option if someone can do it the proper way. because this engine is which came with your car, everything works fine, you dont have to do anything else, electrical, mechanical compatibility and mounting changes etc.
in overhauling you just take out the head, strip the block, put new crank, new pump, new bearings, new main seal, new pistons, new rings etc and you are good to go for thousands of kms. then you know what has been done, you are sure of everything.
if you change or buy a new engine, you dont know its history, you dont know what will happen to it after driving it for some time. i mean even of you take it from a known person, even then you dont know what that engine has gone through its past life.