Certainly looks like morse taper, and the dimensions you give suggest MT3. So the collet chuck you pointed to should work OK, especially as it also is M12 for the drawbar. You might be looking for ER20 because you already use that collet size somewhere else so you have a range of collets, but ArcEuroTrade sell ER25 collet chucks on an MT3 shank. However, I suspect that ER20 will hold as big a cutter as you would want to use on that machine - it will take a 1/2" shank cutter; ER25 goes to 16mm/5/8". Main advantage of ER25 is that you can also get a ball-bearing collet closing nut which makes it a bit easier to get a good grip on tools but in this size, it probably doesn't make a lot of difference.

I've been happy with various things I've bought from RDG in the past, although Arc Euro aren't bad either.