I am doing almost the exact same thing, as I am using 35 spline Strange axles from an 8 3/4 and putting them into a Dana. My understanding is that by using equal length axles, this will offset the center of the Dana. Meaning you would want to check driveshaft angle if your motor is mounted in the traditional manner(off to the right). I am making new mounts for mine anyway, the the motor will probably sit in the center.
Tom