Been wanting to build a smallish cnc lathe, mostly turning aluminum parts. Pretty confident with the whole build other than spindle and headstock since I currently have no lathe, only a mill. Anyone know much about these?

https://dunhamtool.com/precision_spindle_headstock.html#drawings

For 1700 I can get the whole 5c spindle/headstock assembly and it appears to be of good quality but im not sure what to expect. Largest parts I'll be turning is out of 1 1/16 7075 bar stock and i would like to get excellent precision and surface finish. Obviously gonna depend on the rigidity of the whole build but will this assembly be a good foundation for this build? Are there better ready made options to build a small lathe around? If there was a decent option for just a spindle, I think I could possibly mill my own headstock so that's an option too.

Another thing im curious about is using this on my mill as a sort of mill turn setup. 2 questions on that part specifically. How huge of a servo would it take to run this lathe at 3500rpm and also be able to hold position for index work in a 1 inch diameter aluminum part? Is this even feasible using a servo that costs a grand or less? Also even if I can get a servo that will handle this, will a toothed belt on the spindle pulley keep it rigid enough for index work? They have pulley option for 1 1/2 inch wide toothed belt. Would it be more cost effective to use a more reasonable servo and build a brake to lock it for indexing?