The 4350 is fairly darn weak tbh
You have to remember that even though it's marketed as a quad-core, in actuality it's a dual-core chip.
The same scales linearly with the rest of the FX line.
AMD uses 'modules' over traditional physical cores. It's quite an interesting die-design. It means for each physical core, or 'module' there's 2 logical cores inside it. They're smaller and less efficient than a large physical core and they share the same cache with each other, but they get the job done.
The 4350 then, uses two of them.
6350 - 3.
and, 8350 - 4.
The reason it's not so great is purely down to their poor efficiency. They're small cores and as such don't perform that well on their own. The 8350 however, having 8 modules performs pretty decently, but I wouldn't go for anything below that.
With a half-decent AM3+ board you could easily pop in 'said 8350 and have it work straight away. It consumes a bit more power but I'm sure even the most basic of power supplies can handle it.
(Especially if you're considering a second card).
Two 760s would be quite a nice setup, something I don't think the 4350 could handle on its own. I'm not sure about the 8350, but it should be alright.