Needing help on a 350

[Sal's '55 Chevy]

My brother is building a carb 350 for his 88 chevy truck, he is using a 88 350 block, bored 30 and decked, steel crank, flat top pistons, 5.7 rods, roller cam that has a 280 duration/525 lift, matching everything else to the cam, double roller chain, high volume pump, vortec heads with port and polish work,screw in studs and guide plates, not sure if he needs self align rocker arms or just aluminum rockers, rpm air gap vortec intake, msd dist with out vaccum, msd 6 box, holley 750 double pumper carb along with a electric pump and fuel regulator,and a set of headers. Do you change the valves in the vortecs and go with 202's or keep the 1.94 on vortecs? What do you guys think about this build any suggestions,changes or ideas? What horsepower should it make?