..........power expectations........

IMO, if we assume the car has power steering and alternator I think the 360 Magnum would net out closer to 240 when the '74 components were bolted to it. The Magnum accessories are a slightly lower draw and the mechanical fuel pump will factor in too. I think I would work with what was in there unless it's got issues. A simple bolt in cam, better exhaust, and performance tuning can make an easy 20-30hp and tq more with no other changes with much less effort.