Advent "the Loudspeaker" woofer Question

:confused5: Hi All!....It seems the only time I appear 'round here is when I need member help. You might remember me from such classic posts as "Paragons - Bonifide? or 'White Van imposters?". I hope you'll be encouraged to know that I've discovered a new level [Higher] when I recently bought a pair of Advent "The Loudspeaker" bookshelf units.
Bookshelf my *ss - they weigh 40 LBs or so each. The problem I'm facing is - 1 woofer was remaining whose foam surround had rotted-[Shades of "The Andromeda Strain"!]
No worries I thought - I had a pair of JVC's it happened to. My problem is - I'm not sure
what size proper replacements should measure....Is it 10" or 12"? The dimensions of the remaining woofer cone/foam look 10" but the mount is definitely 12" - [Frame/masonite].
10"ers that I've looked at will drop right through without a 'mod'. I'm hesitant to 'lowball" the project even though I only spent 10$! for both. And I'd really like them to have as close as possible 'factory' specs. They have a date of '75 and the 3-way switch/post type terminals and I've refinished/regrilled the cabs. They look great....I just hope I can get them sounding as well, so any help/opinions/advise will be more than welcome. Refoaming is out since I only have the 1 woofer left. [I'll send it to whoever for post costs if they'd help me
out]. I hardly ever browse the forums for answers so who ever could send me a reply should just E-mail me at greystoke144@shaw.ca
Thanx, Rick P. from Kimberley B.C.:17:

I sent you a mail...

and I nearly forgot:
refoam both the woofers, not just the one with the rotten surrounds...

Keep them spinning,
Bert.