If the kit mfg has been in business awhile, you can make book on the angles they build into the firewalls of their planes. If it's a plane that was a really great price, it might or might not be appropriate.

The amount of down thrust really seems to be fairly constant. The amount of right thrust is usually constant for an average airplane, for example one that doesn't have something like really short wingspan (like triplanes ).

With established mfg's like Great Planes and Hangar9, they seem to take care to either develop the model with some care, or insure the stuff they get from China is tested and fixed before sale. You are sensible to wonder about earlier versions. On the other hand, the earlier version would have had a problem with a different thrust if this later version shows it being there. Make sense?

If the provided motor mount screwed to predrilled holes for it puts the prop shaft where the provided cowling has a hole for it, there is a good bet the right thrust is going to be a good idea for your plane.

Also, you're not usually going to see really bad things from too much or too little side thrust until you really start pushing the envelope.