The most obvious choice for p65 to pdf conversion would be to use old Adobe PageMaker to get your PDFs. If you do not have access to the original program, you may be, at least particularly, successful with Adobe InDesign.
Unfortunately, PageMaker .p65 files are not supported in many programs and as far as we know no 3rd party programs exist that still support them or that could be otherwise used to convert p65 to pdf.Open P65 file Open PDF file
Professional desktop document publishing software from Adobe
Mac version od Adobe's popular document designing and publishing software
One of the first desktop publishing programs on market
Mac version of once popular publishing program