I would have changed a lot from episode 7 onward; that's when I think the whole thing really derailed even if I am somewhat satisfied with the final product. For starters, I'd have Jack have a different inner struggle against his own demons that requires a bit more of thinking, borrowing some elements from the Mad Jack episode about non aggression being the way to stop the spirit tormenting him. Ashi, on the other hand, would have had to fight her mother and perhaps some cultist from the get go, instead of wasting time with an entire army. That part was incredibly pointless and took away from a much more meaningful battle.
Also, Jack doesn't get his gi and such with the sword; just the sword itself.
Later on on episode 8 I would have had a scene in which Ashi and Jack wash off the blood from their fight against the Priestess in a lake within cave, in which Ashi helps Jack shave and they make love under a waterfall because I love that visual. That's the first half, for the second one they look for the Scotsman and his army, and prepare an assault against Aku.
Then we get an episode and a half (30 minutes) devoted to the final battle and the last 10 minutes of the final episode dedicated to the ending, whether it is Jack staying on the future or not, I don't really care. I would however have Jack personally kill Aku from the future since that's the one whom he has grown to hate through the years.