The best way to look at this is a cost issue.
If you shop around you can find a pretty good deal on a set of ED's.
1400 to 1500 for a set and if your in the US most will include shipping.
Your "G's" will need pretty much everything?
Seats, guides, valves, springs, keepers and a good dose of machining.
The tab will be close to if not more than a set of ED's.
The Ed's are basically a replacement head for 390's.
Out of the box the ED's will have smaller holes than the G's, just the valves are a bit bigger.
I'd put money on it that you will have more torque with the Ed's.