Thanks for all the replies, nice to know " normal " rosin core stuff works well, it has for any of the other things i used it on, even done a very touchy 70mm Philips electret recable.
All great replies and appreciated very much.
Honestly I dislike the silver stuff but was expecting that to be the suggestion
Was going to spring for Cardas stuff but honestly I don't need a roll that will last the rest of my life.
I've got zero room for error on this particular item, so also covering the drivers up is a welcome suggestion also.
Funny thing I am still to this day using some old 1950's(?) hand held thing I inherited from my Grandfather and have it mastered more or less ( did voice coil with it once even ), still even has a decent tip, not like the newer stuff it seems that burn out, but this project might make me plunge into one of the Hakko units i have been looking for an excuse to buy to nail the temperature properly the first time.
Just the thought of getting heat near the moisture guard/dustcovers makes me cringe, maybe i can see about leaving a pigtail of the prexisting contact, hopefully it is not in as bad a shape as the rest of the cable in there.
Thanks again to all for all the reminders and advice.
I have the Hakko FX-888D and it is a very nice unit for ~$100. The digital readout is very handy. The Weller version is nice also, but more $$.