cam question

thanks for the above. heres a little more info::::

the rear gears are 3;55. the tranny is a 727 with a mild shift kit. it has the stock x heads and manifold. unsure on the convertor. this motors very virgin. on the manifold however i would like to swap it for an edelbrock performer. with this manifold would the comp cam 268 be compatible? in the future i will be doing a total rebuild back to the older 10:5:1 specs keeping the above mods. but in the meantime im just looking for some simpler less expensive additions for a little more steam. the motor has 84000 original and runs way to nice to tear it down yet. in light of that what do you guys suggest on these 2 proposed mods?? thanks again.