They're looking for natural and not chubby. Those chubby are rather within that niche, than within the big tits niche.
As for sponsors, check them out:
Traffic Cash Gold - $35/trial - big tit patrol!
CECash - has 3 bit tit sites, free trials for which you get paid (+ for monthly renewals + 50% of all dialer revenue), free content, weekly payments, reward points, hosted galleries,
Topbucks has 2 big tit site, hosted galleries, bannerless free hosting, free content,
Adult Platinum pays $40/trial, several big tit sites, hosted movie and photo galleries, content,
Gigacash has 2 big tit sites, real tits and fake tits, $35/trial, hosted galleries, content,
Silvercash - $50 (FIFTY)/trial! has 2 big tit sites and a small tit site, bannerless free hosting, FHG, free content.
Porn Access with movie and pic FHGs
Reality Cash - $40/trial popupfree! with a brand NEW big tit site.
Traffic Gigolos - $40/trial with a nice big boob site,
Adult Elite
High Def Riches
OCCash - 50-60%
PimpRoll