Eric, I checked out Spal's site and it's got links to PDF's showing specs & measurements of all their fans. It looks like that 16" unit will fit after all. The 2.05 depth is for the motor and the rest of the assembly is less than 1.5" deep! Amazing.
Rich, here is the link:
http://www.spal-usa.com/html/pgtablel.htm
In my cyber travels I also came across a dual 12" assembly - from Perma Cool I think - with a chromed or polished housing that pulls over 2000 cfm and would look awesome as a puller or a pusher (albeit non-original for the purists) if I can only get it to fit. Spal's unit definitely will.
Thanks for the replies.