I doubt it'll have less accuracy than a modern 7x14 would...
Indeed it could be better; it looks more substantial than most of the cheap Chinese models around.

As far as checking the dovetail, part of the issue is trying to decide what reference point to use. There are three possible ones, the rear face or one of the two inner faces. What I cant tell is whether the inner faces are ground well enough to be a reference, and the rear face is the one thats likely to be worn.
I think I'd start with getting the top surface flat and as level as possible (taking the extreme ends as a reference). Have you got a good precision straight edge?

Does the tail stock run against the inner edges? If so, any sign of wear?

The inner edges will have been machined at the same time as the two reference edges, so if they aren't worn too badly, they should at least be straight and in line with the original spindle. If you use a smooth parallel up against them to average out any 'lumps and bumps' you should be able to get a pretty good idea how far the two outer reference edges are out.

If I were doing this by hand, I'd flatten and straighten the rear edge before tackling the dovetail. Use a right-angle and a gauge pin (or the shaft of a carbide milling bit) to check the dovetail.

If you know someone with a good sized milling machine or surface grinder, they probably align and skim all the edges in a couple of hours.