Basic Magnum question: Safe maximum RPM on stock internals?

Yeah I shoulda bracketed that part about chassis issues, and written ors instead of ands.I'll go fix it. The only info missing at that post was the gear size.
The 2.73s are really only an issue A) outta the gate, and B) over the long haul.
As to A) The lack of torque multiplication at the start line makes it lazy until the motor comes into it's powerband, say about 35/40mph.
As to B) The long gears force the engine to spend a lotta time in each gear, at rpms outside of it's powerband. That makes for a poor E.T.

Then there's the timing thing.Insufficient power-timing will not help performance; too much will damage the engine.
And fueling? Fat is safe, but lazy. If you had 420 hp you can afford to give some up. But at 300 it's nice to have them all snorting.Lean is mean, but can be dangerous.
The 2.76 gear can be a tremendous tuning aid, exactly cuz the engine stays in one gear for such a long period of time. This gives the plugs time to build a picture you can read. Or gives the O2 sensor a nice stream to read.
First gear should be good to over 60mph, second to 110.
Just 2 gears in the Qtr will seem lazy alright.