How many LBCs? Box beam size?

[ccamley@mmm.com (Chris Amley - 3M Co. - St. Paul, MN)]

There was a recent post re the estimated current population of MGAs.  As a TR-3
owner I'm curious about how many of *those* might be around in North America or
worldwide.

Also, I know Ray Gibbons did *not* suggest building a box beam from 2x4s and 
1/2" plywood to help suspend an engine.  He did *not* suggest laying it over
several trusses in the roof.  Hence, if I did this and the whole garage fell
down, my wife could blame me, but not Ray.  But if he *had* made such a
suggestion, what size would he have suggested making the beam in cross-section?
                     
                |XX|  ^
                |  |  how many inches?
                |  |  |
                |XX|  v

Thanks
------------
Chris Amley                             ccamley@mmm.com
TR-3A TS39449L