10.5-1 is fine with pump premium in most places.You did'nt mention what intake and carb you have now.

I would suggest a smaller cam(would probably call fast68 and give him all the info he asks for).It will depend on gears,headers/manifolds,exhaust,intake/carb,etc.

I would think a performer rpm or a holley street dominator(hood clearance may dictate)would work very well.

A holley 950hp would work well but so would an 850dp.

Keep the engine you have as selling it will net pennies on the dollar spent.