I agree with toxcrusadr somewhat. As long as the cabinets are sealed back up well, they are very likely to still sound PHENOMENAL, assuming the the following is performed:
1) DEFINITELY, definitely, definitely, replace the current old, out of spec, capacitors with modern “like value” units.
Most likely that will be an 8 or 10 uF (microfarad) capacitor. Huw and many, many of us use the Dayton Audio 10uF Polypropylene capacitor from Parts Express. They cost a couple of bucks a piece, currently
$4.79/ea
If you wanted to keep nearly identical voicing from when the speakers were made and “save” a couple of bucks per capacitor, you could also use a modern Electrolytic non-polarized capacitor, currently
$ .71/ea at Parts Express. These won’t last as long or perform “as precisely” as the Poly’s above but they will certainty work and sound great, especially compared to the original capacitors currently in the speakers.
2) Become a subscriber to AudioKarma, currently $25/annually (I believe) and get access to
Barter Town and watch for or post a WTB for Epi/Epicure 8” woofers. You must ONLY USE Epi/Epicure woofers OR
Huw’s modern replacements, which you are already aware of. IF YOU USE ANYTHING ELSE, you are wasting your time, money and effort. Just use the right stuff from the get go, please take my word for it.
Replacement units can be found on eBay, etc as well, but I like to support the site where I have learned so much about this great hobby, so I support it when and how I can, thus become an annual subscriber/supporter.
3) Epi/Epicure air-spring tweeters are capable of handling a Sh*t Ton of power and almost always are blown because they are/were UNDER DRIVEN and the distortion causes a meltdown. Trust me, don’t worry about over driving them.
4) less critical but worth the effort, replace the terrible, junky, most likely mostly or completely broken speaker terminals UNLESS you have already the
5-way screw-type terminals which I believe were what came on the 400’s and 1000’s.
These are worth the time and effort and will reward you many times over if updated as detailed above and driven with something that can CONTROL the woofers and not just “drive” them.
Do you have any more pictures you can share of what you are working with?
And where are you located?