Blaster top end/engine

I need some sort of engine to put in my 95 blaster frame. in my opinion, i think blaster engines should be blown off this planet. they are he most worthless engines ever built, they are very unreliable and old, havent been changed since the early 80s model dirtbike. and i was possibly thinkin of puttin a YZ250 engine in it, if anyone has any ideas or any engines theyd get rid of, let me know. thanks alot