Actually when I went out looking for bikes my ideal if someone would build it for me would be a nice light 750 twin. Maybe about 400 lb.
The Kawasaki w800 was close to perfect in that regard but it was never sold in the US. And they stop production recently.
There are naked 900cc fours that weigh in at 428lbs, you know. 400 isn’t all that light any more. If you want a ~400lb twin, you can go buy one of the 700-800 class Ducati Monsters or the Guzzi V7 or if you want to go ‘heavy’ at 471lbs, there’s always the Triumph Bonneville.