5 Speed For My 340?

I put the 833 OD out of a Aspen in my 70 340 Duster and love it. I do mostly highway driving so I wanted OD and could no way afford any of the 5 speed conversions. With shipping, duty and the Canadian dollar it would be in the $7000.00 range.
I do not race it but have done plenty of burnouts and lots of playing and have had no problems thus far.
Mike