1. Calculating balance points, and also its relationship to mass and swingweight precisely is pretty basic. Nothing wrong with "going out there and seeing what it feels like" then adjusting intuitively, but that approach is not going to be workable for anybody doing customization professionally, and certainly will not work when the task at hand is to match 12 frames to the nearest 1/2 gram.
2. If you have increased weight in the handle end by swapping grips, then you need to add more mass north of the balance point to maintain balance. How much you add, and where, will also affect swingweight, recoilweight and twistweight. All of that can be calculated in advance fairly accurately as well.
This will tool/worksheet will calculate the affect of placing lead in up to five locations.
http://twu.tennis-warehouse.com/learning_center/customizationReverse.php
This is a bit simpler method. Might work if you have specific aim point in mind.
http://twu.tennis-warehouse.com/learning_center/customization.php
This conversion cheat sheet will be helpful with using the two links above.
Metric Equivalent To Balance Points For A 27" Racquet:
34.30cm = 0 Even Balance
33.98cm = 1 Points Head Light
33.66cm = 2 Points Head Light
33.35cm = 3 Points Head Light
33.03cm = 4 Points Head Light
32.71cm = 5 Points Head Light
32.39cm = 6 Points Head Light
32.08cm = 7 Points Head Light
31.76cm = 8 Points Head Light
31.44cm = 9 Points Head Light
31.12cm = 10 Points Head Light
30.81cm = 11 Points Head Light
30.49cm = 12 Points Head Light
And my thread on grip specs might be useful
http://tt.tennis-warehouse.com/inde...pecs-weight-thickness-into-one-thread.465717/
Good luck
-J