Fallout has big number of guns and only few of them is usable to PvP. I like BIG GUNS firepower, i dont have nothing personal against this weapons, but it is boring if your PvP are reduced only to two guns..
Big guns are the most powerfull and most easy to handle in PvP. Forgot about leveling and supporting this gun with ammo. As i told before wipe, the economy will not affect the PvP. The prices of ammo should be multiplied and this changes will afect the game play too much, so leave the economy modification.
Let the firepower on the same level as it is and change the hadnlig (i dont mean perk). Why the most powerfull class is the most easy to handle (enter area, push a button and click click click, R, click click click? Biggunners should more think about their AP and time economy.
I.e. As a Minigunner, you will enter the city, you will see enemy, them you will burst your three rounds and then you will need to reload. That will take some time. So you must get from the first line for some seconds or cooperate with your assault riffles teamates which will reload much faster and they can fire almost constantinously.. That will be the biggest difference between those two builds. You will need to make your team more balanced then now. Also pursuit of the enemy will be ideal for smallgunners and snipers instead of biggunners (no run with big gun in active slot).
Hope the fights will be more longer then, if the number of BG will be little reduced. I though that fight lenght was the main reason why devs reduced the criticals for snipers and they disabled instakills. But they forgot, that BGs have their own kind of instakill (3x push button).