Best Crank Length for 9 ft Giraffe

Long story short, I was letting my friend ride my 9 ft unicycle and he fell off and landed on top of a brick pillar. He was okay, but the cog bent and it’s no longer rideable. The cranks and cog were connected as one unit. Basically to get it on and off you have to unbolt the side and feed it through the hub. Now the current (will be previous) cranks were the same length as on my club 20". I believe it’s either 114 mm or 125 mm. Idling on it was doable, but felt awkward because it was so heavy. That was also before installing a temporary chain tensioner. Since I am having to replace parts anyway, I’m wondering if longer cranks would help idling feel smoother. The main thing I plan on doing on this is riding forwards, backwards, idling, one foot idling, and juggling. One foot riding would be cool but that sounds sketchy on a giraffe this tall.