I’d agree with Donovan,
If you’re just after reducing the noise then start with an enclosure and then do the expensive stuff like VFD spindles. There’s a thread where I made some suggestions based on tested recording studio sound control technology for making a Shapoko quieter.
I would wait for the Z plus to come into stock rather than trying to build my own (unless I owned a milling machine).
As for the spindle specs, the 220V and 110V versions of the spindle may well be quite different, double the current is a decent ballpark but I’d want to see the spec. A 110V VFD will not be usefully able to drive a 220V spindle and a spindle with excess current draw will likely cause the VFD to trip out in overcurrent protection mode. Also, in case you’ve not tripped over it yet, VFDs that run on 110V but drive 220V have a step up conversion stage on their input and are considerably more expensive.