Hi Eric, the Admirals are easy to work on, wide open chassis. Somewhat hard to come by and expensive though.
Avoid any and all Philcos from the late 40's early 50's cramped horrible chassis.
I have to agree with Tim, the Motorola 7" are the simplest things out there, except perhaps for the 1957 GE/Hotpoint 9" portables like this:
http://www.vintagetvsets.com/ge.htm which can be rebuilt in an hour or so, can't find many with good CRTs tho.
Eric H