With 75k on it, it all comes down to how abused it is. There's just too many variables to say, but tuning is everything. 7 psi is a lot for the stock block, but tuned properly and not beating on it too much it would hopefully last until you can build a bottom end, but I'd have one ready.
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I've seen some guys that had a blower pushing the suggested hp limits for the stock internals and it last a couple years, then again I've seen guys on 4psi grenade their internals in a week. Most of its the tune and the abuse it's given.