[Texasrocker]

You can leave the orig electrolytic metal housing in place, then add a new cap in place of it under-chassis by adding a isolated terminal-strip. Did you actually "restuff" the orig electrolytic can that blew out? If not, you didnt complete your "re-cap" job from the get-go. Those old Aerovox filter caps either need to be re-stuffed, or, replaced with new caps mounted under the chassis before powering up the chassis. If you blew out a new-cap, ( properly installed with polarity observed), then check your schematic for other possible probs associated w / the B+ under chassis. Look for "shorts" from B+ to chassis ground (-) of your electrolytics.
Depending on the schematic,and circuit design, some 500v ratings orig filter-caps were used in the early sets for extra "surge" factor. Someone may have replaced a orig 500v filter can with a 450v can somewhere down the line yrs ago before you got your set? Ive run across similar circumstances before. Good luck restoring your Philco!