318 Build Up?

I was wanting some info on what I can do to get my 318 to perform at its best without having to tear it down too much. It is already bored .20 over (321 cid), stock heads, very mild cam, 4bbl., edelbrock performer intake, stock exhaust manifolds, 2.25 dual exhaust, Flowmaster 40, 2.45 gears (soon will be 3.21 sure grip), and 904 AT. I now I can't get it to run like my dads 340 6 pak T/A, but I want it to run respectivly to a 340 being a 318. Should I build a 340 or just go for a 360 crate?