I’ve done a web search on the Dominion A.L.Y. 1 Vic but the images are not very clear. The spindle nose from what I can see though looks quite long for a wood lathe and doesn’t seem to have much of a registration at the back of the thread? Do you have a picture of the spindle thread?

I must admit I’ve never seen a threaded lathe spindle that long before. I don’t think you’d be able to mount a Versachuck directly on that, it’s too long. You’re back to either putting a Morse taper adapter in the spindle with a draw bar or having a custom adapter made. The former is the cheapest option though. A blank end MT3 arbor is less than a tenner but you’d need to get it thread cut for the chuck of your choice. Let us know how you get on as it may help someone else. 

Thanks for all your advice guys, I'll let you know how it goes.