First, STOCK Mopar converters flash a little on the high side anyway. Usually in the 1200-1500 area. The stock Mopar high stall was around 1000 RPM more.
The 340 cars had the factory high stall and were a GREAT combination. 3.55 gears are fairly mild. The 340 cam is really mild. I think it will be perfect with a tight 2500.
Don't cheap out on the converter. Converter technology has come a LONG way in the last twenty years. You can get a converter now that will be tight driving down the road to produce less heat and get decent mileage, but will flash on demand to a given RPM.
Thing is, you won't need a high flash point, because your combination doesn't require it. The 340 cam makes power from idle to 5800 or so RPM. It is a 318 so it might benefit from a tad more RPM, but don't go crazy with it.
