Here's a cpl more attempts to show detail on the square taper.
Backside looks nice and square. Front has areas where the fixing bolt threads rubbed on the spider.
Pics aren't the best, and not sure if this is still an issue.
<<<I looked up the Velobase description and all it says is an ISO 116mm spindle. Since there is no indication if that is a symmetrical spindle, which it most likely is not, the OP will need to measure the end to race and race to race to determine the size for his crank.>>>
Enlarge on this, please.