axle/tube length for a s&s/Diabolo chassis and steering shaft Q


I have a S&S chassis with no rear end, and no idea what to put in it. Does anyone have an idea what axle length or tube length to use on a S&S/Diabolo/Olsen chassis?

And the car's 45 min away at my shop, need to order the collapsible steering column, is it the short one or the long one that speedway/sweet sells?