The 6.17 single speed rear will give you a slightly higher speed top end than the 2-speed in high range, but an OD 5 speed would definitely be a help with either one of those rear axle ratios.
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!