Don't buy a 928 without reading a buyers guide ☺.
Porsche 928: Essential Buyer's Guide
David Hemmings Porsche 928: Essential Buyer's Guide Paperback – Illustrated, 15 Jan. 2014
David is the 928 register secretary for Porsche Club GB and this is a helpful insight into owning a Porsche 928 as a daily driver or a restoration project.
Other buyers guides are available including one on this site ☺.