Here's links to pics of a ctc-15 chassis in a Philco I did, where I just left the old cans in place, disconnected them, and mounted the new caps under the chassis.
The chassis still looks original from the top:
http://www.audiokarma.org/forums/att...1&d=1177725186
But you can see the new caps underneath:
http://www.audiokarma.org/forums/att...8&d=1177725186
I've also seen some guys hollow out the old cans and fit the new caps inside them to maintain a really original look, I've never tried that but I think I've seen pics of it here somewhere.