If you are ordering anyway then I would get 1610's if it's being used mostly as a wood router because you'll want the extra speed they offer. Don't worry about torque because if you use correct size steppers with a decent amount of volts you'll have more than enough torque. If your just cutting aluminium with it then 1605 will be fine with a 1:1 ratio as you won't cut much above 3mtr/min and you'll get around 5-6mtr/min rapid speeds which is more than enough for smaller machines.

Fred's spindles are fine, I have fit dozens and not had any troubles yet, they are pretty much all the same and in general, I have fit 100's over the years, and less than 6 have gone faulty on me.