I've recapped similar speakers, most recently, my AR58S speakers. As in the 3a, it's a 12" 3-way, using dome mids and tweeters. My 58S's used Unicon branded electrolytic caps, which still sounded very good. Though, I didn't measure their capacitance or ESR, as both can drift after decades of use.
When recapping, I always mod 1 speaker, and then compare it to the stock speaker. That allows me to hear any initial differences, and if a balance adjustment needs to be made, I can add small value resistors in series with the capacitors, to compensate.
I do like boutique caps. Most often using Mundorf and or ClarityCap films. With this recap, I used Mundorf EVO Oils for the tweeters and ClarityCap CSA's on the mids. Bypassed NPE's on the woofers. After the recap, the treble sounded great, both open and airy, but the mids were very recessed and opaque on it's upper end. I let the CSA caps play for weeks, without much improvement. In the end, I added bypass caps to them, which helped restore midrange balance. I haven't used ClarityCaps on the mids since. While good with a bypass cap, I found them too rolled off without. Now, I typically use all Mundorf caps. Jantzen and Audyn caps are said to be very good as well, though I haven't personally used those.
Good luck.