Do I need to upgrade the charging system: Likely no on NEED but it may be desirable.. I will elaborate slightly by talking about TWO converters and different models.
Parallex 7300 series (NOT the 7300T) is below what I consider the minimum for a converter (The 7300T is the minimum) this is a single stage unit (2 stage on the T) and charges very slowly, it may never actually get the batteries to FULL in fact, or if it does then like the older Magnetek 6300 it will boil 'em dry (The 7300 has far better regulation than the 6300 did (By the way Parallex bought Magnetek) Thus I've not heard of the 7300 being a battery boiler.
On the other hand Damon installed a Progressive Dynamics 9180 WITH optional charge wizard in my choach. (The 9200 line is equal to the 9180 with wizard built in).
This is just about the best 3-stage made, (In doing lots and lots of research I have yet to find one better, Several I'd rank as "Just as good" But none better)
The next issue is how BIG (Which model in any given line) do you want?
For one pair of GC2, 70 amps is about the biggest you want. If your current converter is say a 35 amp, then going to a larger one will speed recharge You may need to improve wiring to handle the higher current) if that is important to you.