First up any time before bud opening or up to leaves half open is no problem for a repot.
Repotting does not usually slow or hurt a tree. Repotting will stimulate more new growth so can work against developing short internodes and good ramification. In this case I don't think the tree is up to there so no problem yet.
Second:
This tree is typical of many that the grower has a good base but then tries to get to finished to quick - long, tall new leader is out of sync with the lower section and overthickened nodes.
Clusters of shoots are common but quickly lead to local thickening. Need to get rid of those well before this stage. If this responds like mine do, just removing those little shoots now will add loads of callus thickening to those nodes. Really need to get rid of those shoots when they first appear in spring. Check regularly inside the leaves through summer to get them early before damage occurs.
I agree with shortening the trunk. I suspect the previous owner did too but couldn't identify a good spot to chop so took the easy way and let someone else decide.
I doubt the blue circle you've added will be a good spot to look for a new leader. That node is already bulging. I can't see which direction that branch to the left is coming/going but I suspect it would be a better bet for a new leader so consider the new chop line I've added here.
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Remember this advice is just from a 2D photo which does not allow for depth, direction, etc. Check with what you can see in reality before following any online advice.
Chops like this are definitely a setback. Allow 5 years or more to regrow a new apex and branching but it is the only real way to develop a good bonsai trident with better scale.
Very nice nebari and good lower branches. Without those positive factors I would do as the last owner did but this does have some long term potential.