Goku: 100
Fat Buu: 80
Gohan: 63
Evil Buu: 48
Fat Buu: 32
Gohan would have >1.3x edge on Evil Buu which is substantial. Based on Gohan's actions, he was more than willing to eliminate Buu instantly such as when he unleashed a Full Power KHH on Buu's egg. His fighting skill may be sloppy. However, that sort of power advantage is far too large. With Gohan's mindset, I don't see Gohan refraining from using his full power. One full power blast and Evil Buu is done.