I seriously doubt any SB LA Mopar out there will pull in gear with a hydrauic roller cam and hydraulidc roller lifter and matching valve springs up to or much past 7000 RPM, let alone 8500 in any gear Maybe in nuetral or park
I was told by a older guy, drinking Cutty Sark whiskey straight out of a quart bottle at 1:00 PM in the afternoon at the Colorado river back in 1965, that his N/A 392 Hemi motor in his 21 ft. flat bottom V drive Mandella wood hull would peg his 8500 RPM tach I bet him it wouldn't do that so he offer me a ride in it the next morning when he was sober. It would peg the electric tach at 8500 RPM as soon as he went WOT, but it was showing 4300 RPM crusing at around 35 MPH warming up the motor before he hit it hard He had a Vertex magneto on that motor and he should have had a 4 cyl electric tach for it, not a V8 tach. It was reading twice as much RPM when the motor was running, not the true cranksaft RPM it should have been reading. Most of the other, better, high end boats back then had Jones Motorola mechanical tachs driven off of the top of the V drives so they measured the true crankshaft revolutions, not the propeller revolutions.
My message is it is easy to be mislead on many things, especaiily automotive racing parts and storys
On your deal I would shift it when the motor quits pulling hard in second gear, don't look at the tach before shifting, listen and feel the motor quit pulling first and then look at the tach to see where it quit pulling hard Shift it 200 to 300 RPM before it quits pulling hard Don't over revved it