custom classics Sentinel Prime Need help

okay, so I want to do this guy for a classics custom version of sentinel prime..
But i have no idea where to start from.. any ideas as a base transformer to use for this guy??
For those of you who don't know what he looks like here is a link:
http://10fingersdesigns.com/3d/series91/sp01.jpg
http://10fingersdesigns.com/3d/series91/sp04.jpg
http://10fingersdesigns.com/3d/series91/sp37.jpg
http://10fingersdesigns.com/3d/series91/sp39.jpg
http://10fingersdesigns.com/3d/series91/sp40.jpg
http://10fingersdesigns.com/3d/series91/sp14.jpg
any ideas on what figure I can get to use for this guy?
or just go to http://10fingersdesigns.com/
But i have no idea where to start from.. any ideas as a base transformer to use for this guy??
For those of you who don't know what he looks like here is a link:
http://10fingersdesigns.com/3d/series91/sp01.jpg
http://10fingersdesigns.com/3d/series91/sp04.jpg
http://10fingersdesigns.com/3d/series91/sp37.jpg
http://10fingersdesigns.com/3d/series91/sp39.jpg
http://10fingersdesigns.com/3d/series91/sp40.jpg
http://10fingersdesigns.com/3d/series91/sp14.jpg
any ideas on what figure I can get to use for this guy?
or just go to http://10fingersdesigns.com/