As mentioned above, place your requirements in the search and choose from the WGs that come up in the results. You may get more choice with CIM, then contact the girl and ask her if she will swallow. Be prepared to pay extra.
Alternatively, put up a reverse booking. Choose from the respondents whoever you fancy.
The real question should be, why does it matter if she swallows? Your pleasure has peaked as soon as you cum...and that was uninterrupted by her not wanting cum in her mouth. I let the WG decide what to do with the cum. She swallow it, she can let it dribble out of her mouth onto her tits, or if she chooses, she can spit it out immediately. I respect her enough to let her make that call.
