Gin-chan can wait until you published Naruto, Bleach, Dragon Ball and HxH
After that, you can publish Dragon Bleach Piece (Gintama Parody)
Or Super Chuunin Hunter Exam
honestly hxh is more suitable for one piece world which is about exploration & adventure, ninja & samurai were only known at grand Line at most while Shingaku is completely an alien concept in one piece world so honestly it's illogical for mc to draw Naruto & bleach manga this soon.