I cannot pass comment on the value of adding this to this particular make of lathe, but I'm a retired electronics engineer and am aware of the value of variable speed control, even with limited wood turning experience.
A friend bought a school displenished Graduate recently (£50 - eat your heart out!!). Three phase motor - so the options were to look for a single phase one or create the three phases. I bought a suitable box off Ebay for him ( Ebay shop so new item) for around £70, but then found that this produces the 3 phase at 240 v not 440v so the motor required to be connected in delta rather than star; modern 3 ph motor have connection plates to do this - old ones don't, so it was either a new motor or dismantle the existing and rewire - the latter was easier for me as it would not involve new pulleys, mounting plates, etc.
There is then the problem that the 3 ph box needs new control buttons (latching rather than momentary push button), and how to wire in an emergency off switch, etc. So a new control box is required with the speed control in it too.
By now anyone thinking of this modification will get the message I hope that it's no mean task if taking it on yourself. There is no magic bullet as I'd hoped of just connecting the 3 ph box to the mains and then to the 3 ph input of the lathe; that just does not / cannot work I've learnt.
Suitable small 3 ph motors do come up on Ebay for a tenner or so. Having done my mate's machine, I'm going on the convert my Myford.
If anyone is wanting to take advantage of the learning curve (now at least 3 months long) I've gone up, please contact me.
OW