To be clear, the 780G is compatible with the 8320/8350. However, the 780G is an entry-level chipset, so it is mostly found in entry-level boards, which do not have the power delivery system to handle one of AMD's octa-cores, overclocked or not.
It is usually a good idea to try to get a higher end motherboard for the 8320/8350. This will prevent your motherboard being damaged by an overload in the power delivery system. If you already have the motherboard, I would stick to the 8320 or 8320E, as recommended, since I would not want to overload it. If you can get another board, though, try to go for a higher end one, and then you can get a 8350 or overclock the 8320 to an 8350 (the difference between the two is literally only clock rates). The price for CPU and mobo should still be well under the price of an eight-threaded i7 and motherboard, so it shouldn't be too bad.