Yes, school vouchers should be allowed for parochial schools if the schools deserve it.
I don't see why parochial schools should be excluded from being 'publicised' if teh schools really do deserve it. Just because the school is taught differently from the traditional schools doesn't mean that it is all the worse for it, and should be excluded from benefits.
Not only that, but from the students and parent's perspective, parochial school vouchers should also be allowed. This enlarges the student's choice of schools, and hey, why not? If the parents are so adverse to their children learning in a parochial school, then don't enroll them there! But for the parents who would like their children to be educated in a parochial school (maybe for religious reasons), issuing a school voucher to a parochial schools would save them a lot of time in having to appeal for their child to be allowed to attend a parochial school.
Also, one of the purposes behind the school vouchers were to encourage free market competition between the schools. This competition would force 'bad' schools to review their education system and improve themselves. Parochial schools should also be given that opportunity.
School vouchers should definitely be allowed for Parochial schools.