Where is your balance point and what do you consider ideal? 10% FOC is generally considered about right, maybe less for flight, more for hunting.
I don't think the changes you suggest will appreciably effect the spine.
Obviously it's very difficult to match absolutely everything without sorting through vast numbers of shafts by weight and spine to produce sets of matched shafts. Even then there may be rogue arrows in a set that don't group.
Which factors need matching may well depend to some extent on the shooting (I'm guessing here). Longer ranges may be less tolerant of balance point, short ranges less tolerant of spine? Dunno, you'd have to be a good shot to notice the difference.
I think your proposal of matching is a good start point. It can be done by adding or subtracting weight from the points . Drilling into the head to loose weight or adding solder (or drilling a hole and inserting a small length cut from a nail) to increase it can do the job, but its probably better to match the shafts in the first place.
I s'pose you need to define your margin of error, maybe matched to with 10 grains?
If you want to adjust the balance point and weight, sanding a little off the diameter at one or other end can do it without effecting the spine appreciably.
Dunno if this rambling response is any help.
At the end of the day, actual performance is the real arbiter ...
Del
PS. Dunno if you've seen this FOC calculator, it's handy. I use it for my flight arrows.
Arrow Front of Center (FOC) Calculator