If you really want to make more power then get some good aftermarket heads. in most cases, ported stock heads are nearly as good.
what gears, what stall, what compression? all these things need to match along with the cam used.
a 270H is a good all around cam. With a large engine like the 388, it should run well with a wide range of parts. 3.08 to 3.55 gear, 2000 to 2400 stall, 9 to 9.5:1 cr.
I would run the performer intake over the torker. You may need to use a carb adaptor on the performer intake as most of those intakes use a spread bore pattern. How much hood clearance do you have? I would prefer the performer RPM intake with a square bore pattern for the holley.
don't expect good mpg with a 700DP. A 3310 750 vac secondary carb would be better for mpg.