Stirring up a hornets nest

Early A Bodies have a huge weight advantage over later ones don't need nearly as much power to have fun. I'd follow toolmanmike's build it probably exactly what you want.

The biggest hurdle with a 273 is torque most engines produce around 1.1 to 1.2 lbs-ft per cid which put you a hundred lbs-ft under a 360.
Of course you could drop in deep gears to compensate but tranny is the best way either a 904 from the 80's with deeper 1st and 2nd or even better the overdrive version of the 904 which will give you deep gears and the O.D gear so you can go a little deeper in the rear too.