1 Ideas

OC starts off with some sort of legacy maybe the whole naruto worlds legacy maybe in system form where he needs system points(SP) to get bloodlines and kekkei genkkai

Should he have knowledge of both worlds or just naruto or dragon ball? Should the system be smart or just a store where he buys stuff? If there is no system how does he get the powers of kekkei genkkai or ninjutsu?

How would he meet the gang would he happen to have a dragonball that leads to him or would he be found in the woods by grandpa gohan and be a brother figure to goku? Maybe he is grandpa gohan's actual grandkid and grandpa gohan has the naruto legacy ninjutsu and taijutsu and whatnot?

In dbz he is going to need to have rinnegan and otsutski bloodline to do anything maybe the ten tails too i could nerf the dbz universe or buff the OC so that the worlds are more equal

He should fight with taijutsu as his main while ninjutsu is more support for when the dbz characters use ki blasts i mean even in the naruto world regular old ninjustsu becomes more and more useless since you cant really effect any of the ten tails jinchuriki with it

Maybe something like an otsutski child got lost in a space rift after eating a chakra fruit and landed on earth but in the dbz universe he hit his head and forgot who he was or where he came from when he later got picked up by grandpa gohan along with goku he survived the ozaru transformation since granpa gohan gave his life to save him from it the adventure continues with him goku and bulma trying to find the dragon balls thus developing his powers.

Maybe some added things like a transmigrator replaced the original otsutski when he hit his head so that theres a direction for him developing his ninjustsu?