looking to increase performance

I own a 1973 barracuda 318 2bbl. with little cash i would like to increase performance using the december 2003 318 hipo article. the only enhancement to my bone-stock unit is 2.5 inch duals with flow masters on stock manifolds. the 318 article doesn't state the year motor used, but i believe it to be similair.they used the comp xe 262h cam and tappets, mopar performance intake and edelbrock 600 afb carb.  with this combination they pull #'s comperable to the 68-71 340's (282hp @5100 rpm & 340lb torque @ 3600 rpm)can i expect this much increase?what if i go with the cam set, but use a 340 or 360 stock manifold and thermaquad, will performance suffer, if so, how much? i will also be adding a windage tray. what type of performance can i expect? eventually, i will be adding a 3:23 or 3:55 gear set-up.  thanks, bob