Spindle Motor Advice

I've just ordered a belt drive kit for my BF20L (G0704 to those across the pond) and am looking to replace the stock motor.
Please don't suggest a treadmill motor, coming from the repair\service industry for exercise equipment I don't want to deal with one nor the controller.
I have been looking at a brushless DC motor here:
www.emppl.com.au/collections/brushless-d...1000w-3500rpm-m090-l
or the 750w option
www.emppl.com.au/collections/brushless-d...-750w-3500rpm-m090-m
Along with their recommended controller, on the surface it looks expensive but the supplier is in Australia, so should have a saving on delivery costs.

Or would an AC servo motor be an option such as:
dmm-store-shopify.myshopify.com/products...-75kw-ac-servo-motor

What other options are there ?
Keep in mind that almost all my milling projects have been in steel so far. If possible I would like something with a 14mm shaft

a 3 phase motor with a VFD would be the cheapest option if you can get one the right form factor.

I though of that Rod,I have one for the Myford ML7\Super 7 I'm putting together, but it weighs a ton and I'd have to upgrade the Z axis motor & drive to cope.

I'll give emppl a shout Monday and see what they reckon.

I used this one on a Sieg X3 which is very similar to a G0704. It drives the spindle via a toothed belt geared 1:1.8 so I get 5400 rpm at the spindle. My goal was higher spindle speed and being able to do rigid tapping. Both were achieved.

DMM-DYN4 1.8kw

I opted for the 750 watt from DMM, the local supplier never got back to me, could be something to do with the hipsters in Melbourne and the beverage plague.

Was going to go thru one major US supplier but they were $110 USD more for delivery than DMM.

Johnny have you any tips for setting up the DYN4 as a spindle.
I'd guess I'll also need a 7i83 for the analogue voltage to control the DNY4.