I don't own a system with an A6-3620, but I have the higher-clock variant with the same on-die HD 6530D GPU; the A6-3670K (A6-3650 with an unlocked multiplier).
Heat should not be an issue, as the heatsink design, etc puts into account the CPU and GPU portion of the chip. C'mon, AMD isn't thaaat stupid .
As a side, I have my chip overclocked to 3.2GHz (vs 2.7GHz stock) for the CPU, and the GPU clocked at 500MHz (vs. 444MHz stock) and the stock heatsink is holding off okay. It's a little on the warm side, but still well within spec.
At stock speeds, I had no problem running Starcraft 2 on Medium (with some settings on High) at 19290x1080 resolution. We are also talking about 4v4 online match with atleast one zerg player (me ) putting creep everywhere. I'm sure you should have zero problems running the game on atleast Medium.
The A6-3620 is a 65W TDP chip...and the 3670K is 100W. If it has no problem cooling my chip, it should be more than enough for yours.
FX-8350 @ 4.8GHz // ASUS Crosshair V Formula 990FX // Sapphire Vapor-X HD 7970 + Dual-X HD 7970 // Thermaltake Frio w/ push-pull (using Antec Formula 7 Nano-Diamond + Cooler Master JetFlo fans) // 8GB (2 X 4GB) G.Skill RipJawsX 2133MHz // Corsair TX850 850W // Corsair Force GT 120GB SSD (OS) // Kingston V200+ 120GB SSD // WD Caviar Black 1TB // Windows 7 Ult x64