they're absolutely the worst of the Z's (transitional smog compliance ?)
They were actually faster off the mark than the 280z (none of them were particularly blazing going from 0-60) & had a faster top end speed than either the stock 240 or 280.
Those are the 240s and early 260s.
I owned an '75 280z about 20 years ago, I loved that car.
I'm not familiar with the first fuel injected cars (260z), but they had it working good by '75.