RV-3Bs seem to vary between 733 pounds and nearly 900 pounds, although some will be outside that range. Generally the heavier ones will be IFR equipped.
I'm hoping that the one I'm building is no more than 850 pounds but we'll see. It'll be VFR day, but have lights and autopilot. It does not have an inverted system and will only have one com radio. It'll have minimal electrical backup.