Hi!
If I recall (correct me if I'm wrong), the value of units with hit location templates is the collected value of all hit locations and that is the value for the "armor" part of the equation.
My observations are:
A. Not all hit locations are created equal.
The rear template in particular takes fewer hits if any during a standard game. Perhaps a steep discount, maybe half (or less of a full value frontal hit location.
The sides are more common, so perhaps 75% of a frontal location.
B. You don't need to penetrate or destroy all hit locations to eliminate a model.
This is a tricky one, because how do you calculate or valuate the highest yield hit locations (the ones most likely to yield VP) and assign the highest value to those while assigning less value to those which the probability of VP yield is less.
I think you could possibly use the damage tables to determine that, but that may be difficult, especially given the probability of changing them in the future.
I guess we could look at one set of values with calculated as you did the original ones, but with perhaps 50% and 75% value for rear and sides hit location templates and see what that looks like and another set of values where a locations value (regardless of side or rear) are weighted according to the possibility of yielding VP versus those with less likelihood of VP yield and compare those sets and see what that gets us.
The first alternative maybe the easiest, although I do dislike that just the numbers of hit locations wears heavily on the cost as its drawback.
The second maybe somewhat difficult to do, but I think we all know what the high yield hit locations are and those can be given a full cost (or even multiples of full cost) and the rest a lesser value.
Another possibility as I wrote this occurred to me. There are only several types of locations in each template (head, weapon, reactor etc.), why not assign a cost per "area" then either add or multiple all the hit location boxes of that are together for a cost per "area"?
For example if I i were to say the weapon hit location has a value of 25 points (all values are just examples) because weapon spots have a lower possibility of destroying the unit outright, I would then count the total number of weapon hit locations then multiply by the base value. So if it has 6 total the total for that spot is 150. In case of the head, which is a high yield location, let say base 100 points x 1 location (if only one exists), then that is 100 points and so on until all the distinct areas were done and totaled together.
I tend to ramble a bit when I do this types of conversations so feel free to ask, re-ask and explain anything that is not clear.

Primarch