Darren,
There is a great difference between surface grinding and setting a machine up to basics.
A standard mill cannot give you the continual accuracy of a surface grinder. It is all to do with the way they are made and work.
But when setting a machine up to basic settings (tramming, levelling etc) you should always use, if possible, the machines original ways or table. If say you put a surface plate onto the mill table, any error in that surface plate will be directly transferred to the machines settings. So say you tram on a surface plate that is sitting on the table, and that surface plate has a 0.002" error on it, when you tram, you will be automatically setting your machine up with that error.
If you are happy working with that sort of error, then fine, it is you that has to make the parts fit together.
I was just informing the members that errors in setting your machine is reliant on getting the most accurate results you can, otherwise, why bother in setting it up in the first place.
As an example, if your tram is out, how can you expect to bore or drill a hole truly vertical if using the quill?
John