Depends on your definition of "street photography."
You say you favor spontaneity. If you want to do handheld fast-paced zone-focused work, then you'd need to hit something like 1/250 @ f/16 or higher with that 80mm lens -- so if most city sidewalks are shaded, figure that even ISO 400 will only give you 1/250 @ f/8, SO..... fuggedaboutit!
[/list:u:a3aabce974]Look at pushing, using a highspeed film, or working some other way (like: spending the time to focus).
- [color=#505050](Fort Street, Honolulu - 6x6 Delta 400)[/color]