Will a stall converter with a 3500-4000 RPM engagement do me any good on a stock 350?

Stock 350 engine or stock TH-350 transmission? Either way- a stock engine with a 3500rpm converter will do very little as a stock 350 engine is designed to operate optimally in the 2500-3000rpm range with rear gears anywhere from 2.73 through 3.73. I think putting a 3500rpm stall behind a stock engine with average gears of say 3.08 (or worse 3.73's) you would see a slight "improvement" at takeoff (with alot of noise to go with it) and a huge rise in your fuel consumption while city driving. Using such a converter would also mean getting an adequate external cooler as it's going to slip alot more at lower rpms.

If you have a modified engine/setup that would justify such a converter- the question would be "will a stock TH-350 hold up under the abuse it's going to get"- the answer- maybe.