If that was mine and I was just putting around town with it I'd run that **** as-is, but that's just me. The flywheel is going to hold that crank together. Unless that cut goes past the flywheel mounting flange and into the root of the shaft and into the crank seal area I don't see much of the strength being lost, but I can't really see all the damage so it's hard to tell how much of a butcher the hack with the torch was so take my advice with a grain of salt. Probably going to need a crank seal at the very least though.
Now if you'll be dumping the clutch at 6500 rpm occasionally and shiftin' without liftin' you might want to find another crank.
