I agree with the KB 167 pistons. They also make em forged too tho im not sure of the part number. The 167 is cast. If he goes .040" overbore it puts the bore at 3.950" that to me is close to the magical 4.000" 340/360 bore.
Being its a used block, it would likely need an overbore anyways if its high mileage. Use the 302 type castings, put in stock 360 sized valves, port em out, and open up the bowl areas to un cork the heads.
I am building a 74 318 mild hop up myself, doing something similar.
Matt