Why did they even put it in the game as what is just an FDL but worse. This thing is bigger than a Python, but has small ship optionals and FDL core modules. It feels like it was balanced by an unpaid intern. If all non-utility slots were converted to small slots, Mamba would have 159 while Python would have 395, almost 2.5 times as much. It's an absolutely gorgeous ship, which unfortunately can only do 1 thing reasonably well and everything else very badly.
Making it into a unique, and interesting, ship that can do other than combat wouldn't even be hard and would fit better on a ship that big.
Make it 330t, make engines and FSD 1 size larger, give it 2×5 3×4 1×3 2×2 1×1 optional internals (unrestricted FAS optionals)
Now I didn't mention the fuel tank, because the extra space could just let you expand it without sacrificing 1/5 of the ship and makes for an otherwise unique handicap.
With the class 5 FSD and more flexible internals it could actually explore with that cockpit without having to limp everywhere, though it still couldn't beat Kraits as it's heavier than them. Class 6 thrusters allow it to easily retain similar levels of mobility despite the added weight.
I do understand that almost doubling the internal space will let it tank way better than before, so it wouldn't be uncalled for to reduce the stock hull to 390.
Balancing with jumprange is stupid anyway, let all ships jump at least 50ly when fitted properly FDev. Some of the best looking cockpits are on ships which are almost incapable of travelling long distances in a reasonable amount of jumps without sacrificing everything. FDL and Mamba can't jump 20ly when fully engineered for combat, even with a CG FSD!