The widow maker Z1 ruled until Yamaha did the XS1100. The power band of the old 900 came on steep and garnered that nickname. 'they say', there are a few frames still out in the woods on 129/dragon.
I would get smoked on CB750 even with a 52 tooth rear sprocket and JCWhitney 4-into-1.
Some history on the Z1.
https://www.motorcyclespecs.co.za/mo...ki_z1%2072.htm