What year 318? It probably has a steel crank. I'm not sure the bottom end is the limit here.

Draw through? I'll just say compressing air is a lot easier than air/fuel. Plus increased charge cooling with blow through.

GT45. will make plenty of power, and be straight forward and easier to tune.

Not 2900. maybe if you have a 7.25 rear and no interior. My dart was fairly light for a street car. ~3200 with full bench interior, iron headed small block, alum rad, alum MC, alum wheels, manual steering, glass hood.