just baought a lathe, need to convert to CNC

hi

I don't have loads of experience with lathes, but I do have a Myford ML7 (long bed, norton box) which I've done a few small one-off pieces on

I've just bought a bigger lathe, and want to convert it to cnc... here's the lathe:









I'd like to be able to turn a mincer worm... a bit like this...


but for the big mincers at work, so about 3 foot long and 6inches wide... when I turn it, the length has to be exact, but the actual worm but doesn't have to perfectly match the original (which will make things much easier)

to buy a worm, they're £2500 each ($4000) and made of cast... we make dog food so put huge chunks of meat through the mincers and the worms are easy to break... they also wear around the outer edge, so they don;t fit tight into the barrel after about a year and need replacing... the barrels they fit into need replaying about every 2 years (about £2500 again)
if I mad my own worms, I could probably make a wider worm to compensate for the worn barrel and make the barrels last twice as long

I'm still searching on here and the internet for more information - I've looked before and know what I'm doing / the rough plan... but not which motors I should buy etc..

(I'm good with computers so that side isn't a problem... and my brother is an engineer and spends most of his time doing cad work)

also, I'm not worried about the speed of the machine... as long as the tool can move fast enough to keep up with the work spinning that will be fine by me... (I'll only be doing big one off work) so I figured I could gear down the motors a lot for higher accuracy ?

so.. does anyone have any input ? I'd like to search more and post back here before I buy anything...

thanks

Alan