What's the practical redline for an M42?

[Toby B]

Ok, to explain- if one was to race a car with an M42 in it and the engine
had to go a season (12- 15 SCCA race weekends) between rebuilds,

what's the practical rev limit for the M42?

Assume it's ok to fix oil distribution, stiffen the valve springs, all the
usual things you do to race a BMW engine....

and assuming the above, as you wind it out, what are the weak spots?

Not that I'm contemplating anything like a race engine, or anything...

t