I've heard that referrence to Le Mans or CJ rods being "so old" they may be "weak" several different times. I assume this "age" reference is about rod "service life". The time it was actually used in an engine. Like NOS rods or verfiyable "low mileage" rods would be perfectly acceptable, I would think?
Granted if you have to "re-build" an old rod, I'd be looking hard at new or after market ones. Or if your going to run extreme rpm you can't go wrong with a new "after market" rod for insurance.
I'm running CJ rods myself, which when checked by the machine shop needed no additional work. My motor only had a few thousand miles on it since the last major re-build. I was mainly just "freshening" it with new low compression pistons and a more street friendly cam. Of course all new internals like bearings,
oil pump, etc.
Fired it up yesterday, sounds great, runs smooth, I'm stoked!