I think the most important speed range is always 0 to 300. If you can start a new piece by going from stopped to a few rpm and then increase slowly you will never get into trouble... I also use this very bottom end for doing finishing while still on the lathe.
This lower end is very easy to achieve by using a 3 phase motor and the VFD that are available today....
I have a shop made headstock on my lathe with 4 step pulleys. Driven by a 1725 RPM motor I get 575, 1050, 1725 and 2850 RPM. It suffices for spindle work and small bowls / platters that are reasonably round to start with.
I use the lowest speed for roughing out and for sanding, and 1050 or 1725 for most work. The highest speed is needed for really small spindles like finials.
I do wish that I could get below 575 for some finish work, and I intend to replace the AC induction motor with an 1800 RPM 3 phase with a VFD. That with the 4 step pulleys would get me 0-3600 RPM with good torque.
Since you are building the lathe you may want to consider using three pulleys instead of two. Using three will give you much more control over the speed and get you down to a safe speed (400 or so) if you ever want to turn bowls and have nice speeds for spindle work as well (1800 - 3600).
Many older lathes which were made for spindle work had a low speed of about 900.
A forum community dedicated to professional woodworkers and enthusiasts. Come join the discussion about shop safety, wood, carpentry, lumber, finishing, tools, machinery, woodworking related topics, styles, scales, reviews, accessories, classifieds, and more!