Finally decided on a cam for teen SB. Should I bother with header?

After my first top end rebuild of my 72 e-body 318, where I left bottom end alone, I went in a direction with my comp XE262 cam that would eventually compliment a bottom end rebuild. But things have changed and I probably won't be touching the bottom end for several years at least.

Until then, I could not live with a cam that killed everything that muscle cars stand for, so I ordered a cam that will best fit my low CR, street driving style, stock automatic 904 & converter, shift kit and 3.23 rear. I ordered the comp XE250H. I chose that cam & lifter set because I wanted minimal cost & effort ( Hughes whiplash wanted me to order new springs & tool kit to remove, etc.). It's a done deal. Although hardly a screaming cam, it allows me to maintain my dynamic CR (something previous cam killed), and has a power range right where I play at 800-4800rpm as I have never revved above 3500 in my automatic (previous cam was 1600-5600).

So below is my new setup as I was hoping someone can speculate on my new power numbers, as I also contemplate on the benefit for headers, given my situation.

stock 318 bottom with 84K miles, decent compression, no smoke.
mildly ported/matched 308 cast 360 heads, decked 0.020"
thin 0.028" gasket
current CR now 8.2:1
Weiand 7507 DP intake
Edelbrock 600
Curved spring kit in otherwise stock dizzy
Pro Form roller rockers
comp cam 20-220-3 http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=624&sb=2
Dakota exh manifolds with porting

My guess, I am around 320hp with torque at about 350, but all down low right where I drive my automatic. If I have learned anything, it is that waiting for cams to come to life with my trans and gearing, means I am missing out on low end torque fun.

My final question is about headers. Can't speak toward A body, but E body headers done right means I have to spend over $700, not including the cost of modifying my exhaust system to accommodate them, another $200 or so. So should I bother, based on what you have read? Will I benefit enough to say WOW, or will it be more like, oh yeah, I think I noticed a difference?

Thanks all