A stocker will see just shy of 8000 before valve float.
It will rev happily at 7000 all day long. However it may not take many days of that kind of treatment.
I got a total of 24 months of abuse out of a 4k with regular trips to valve float, but wasn't using it it every day.
Ultimately, some engines last longer then others, but if you keep a stocker under say, 7200 you should have no troubles. :wink: