When looking for further afield records, its alway great to go and spend a day at the specific records office, but it is surprising how much more productive that time can be if ou get chance to explore and browse the online catalogues and collections first, here is the link to the Norfolk NRO Online Catalogue:
Take a look for background as well as specific references and documents connected to your family and project.
Your can visit the office armed with a short list of target documents, see the address below and website
Norfolk Record Office
The Archive Centre
Telephone: 01603 222599
Fax: 01603 761885