What is more common pronunciation for 本文: ほんぶん or ほんもん? Is it geographically specific?
What you'll use every day for text body (main part of text) is ほんぶん. The reading ほんもん is a jargon among historians (inherited more traditional 呉音 pronunciation).
A similar example is 文書. The daily pronunciation is ぶんしょ, which means document, while in paleographic context it reads もんじょ, to mean manuscript or particularly epistle.