By taper bearings do you mean taper rollers like a car wheel bearing? I had ruled these out as I was thinking a car wheel bearing is quite slow speed and high load...Angular contact are they like a front wheel drive type of bearing where its ball bearings but a closed and open side to the outer race?
If I did them out of a common car taper wheel bearing then they could be universal to source and a reasonable price - the loads are going to be a fraction of a car its just the speed and keeping the dust out

The reason I wanted to make a spindle is to be able to have a speed control from the spindle board of the system 4 - I have worked out how to switch the dremmel on and off via the relay but want to progress and use an electric motor / speed controller from an electric model motor if this is possible