Hi David,
The 7D can handle pump supplied fuel, but requires some adjustment to pump pressure. The external Perry pumps work well (at least the crankcase pressure driven ones - I have never used the oscillating variety), but take up some space in the engine compartment where there is typically not a lot available in the classic pattern designs. I am not sure you would see much, if any, increase in power. It is interesting that you mention the OS .61 RF as the unpumped version utilized a barrel type carb with a small throat diameter, but the pumped version used a butterfly type carb (like YS); the only butterfly type carb I have ever seen used on a stock OS engine. The Jett engines are very impressive in both performance and construction. It is basically a custom made engine and I think the price is quite reasonable for what you get. Great customer support for repair or rebuilding even in the event of a crash. They are also very durable even when run extremely hard. Plus they are quite light, I bet the .90l weighs less than the Picco .80.