how much would this build be able to upscale?

[Helios]

Better, but you'll still lag in some games most likely.

Basically, if you want to play dolphin flawlessly on every game, a haswell-class performing CPU at around 4 ghz is required. The CPUs you're suggesting are quite a bit below that.

Lesser things will run for sure, but don't be surprised when games like Rogue Squadron or Super Mario Galaxy lags even at 1x internal resolution.