That's sort of what I was suggesting I would still use the 360 Magnum as a base to work off rather than the old LA far superior motor and stay with the roller cam and yes some sort of OD transmission I'm just not a big fan of automatics although if you have the little 7 1/4 rear with an automatic you can use the 8 1/4 lots cheaper and easy to find remember compression and rear gears kills MPG so if you can keep the compression down with some sort of power adder may help your MPG goals