73 duster questions

A favorable,Power to weight ratio.
Or, failing that;
money, and tools, and friends, and a skilled machine shop,
and FABO, of course.
That's what it will take,To get the favorable P/W ratio.
Or you can just get the weight down to 2700 pounds. Then almost any 360 will get you there with favorable gears and some semblance of traction.But getting to 2700 race weight will be a trick, especially if 200 of it is in your pants, like mine is.

With an automatic and an unlimited chassis, a P/W of .089 is what it will take. That would be .089 x raceweight. or 300hp at 3370lbs/raceweight.
With a street suspension you might need 40 or 50 more HP.
If your car is a fat *** like my 68 Formula S and scales at 3650 race weight, you might need more than 350 hp with a street suspension.That's 3650 with me onboard,and thats 200 pounds of muscle and bone.
No really, that's relaxed muscle. Go ahead, honey give it all you got.