Swapping spindles is a relatively straight forward task for someone who has been taking the wheel hubs apart every year to clean and grease them.

It could be a horror show for someone who has never had a hub apart. A handful of ball bearings will fall out of each hub and need to be put in again as you reassemble the hub. Not impossible, but a challenge the first time.

I recommend taking the bike and wheels to a bike shop to have the job done.