There won't be enough selector positions to align with all the gear positions, so you'll have to count clicks to get to the right gear. Also, the Powerglide shift pattern is P-N-D-L-R, so a car thief would get terribly confused trying to find the right gear! I used to drive the family's 63 Impala with a 327/PG setup 100+ MPH pretty often, so highway speeds with a PG won't be a problem with an engine that can stand the RPM.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!