Something I did to help me find the turret numbers is simple.
Make a test mission and put the ship in question into the mission. From there, go to the initial status box from the ship editor, and for each turret give it a starting precentage equal to it's number.
Then go into the mission, and you can see exactly where each turret is, and map them out on paper or whatever else you choose to do. (consult the ships.tbl for which turret has which gun)
For example, you can take the Iceni:
turret01a - 1%
turret02 - 2%
turret03 - 3%
turret04 - 4%
You get the idea. It takes a few minutes, but you should have no problems getting the job done. ModelView, conversely is a pain because it doesn't list the turrets as they are in the table. Instead it'll have weapon turrets 1-15 and missile batteries 1-4 or something akin to that.