Searching for the ideal vintage bookshelf speakers.

Unclechoppy,
I'd suggest you ask this same question over on the audiokarma forums where there is a much broader, and experienced knowledgebase regarding vintage equipment. The regular contributors there would also be able to assist with required maintenance for speakers on your wish list. Something like the Harbeth SHL-5 would be easier to own, since its still in production, than something like the Allison where replacement parts could be hard to find. Foam surrounds are easily replaced, but you would want to make sure proper sized surrounds are still available before committing. 

From your list, the Harbeths and Spendors would present the lowest risk in that they're generally respected, and could be easily resold if they weren't to your liking. But, I'm not sure how well each of those would work in a near wall environment. I understand Harbeths need a bit of room to keep the bass under control. 

Best of luck with your selection and let us know what you end up with.

Can't comment on all - but I do own and continue to use a pair of Spendor SP1 in my second system.  I recently set them up after a number of years in storage.

They are absolutely wonderful.  A full, rich musical presentation that I can listen to for hours on end. I have them on small stands, and they perform well with all types of music. Never any fatigue.

In my main system I alternate between Dynaudio C1, and believe it or not rebuilt Quad ESL57.  While a case could be made for newer technology, I just can't imagine any more enjoyment than I get from my "vintage" speakers.

yakbob +1 !

Honestly, this thread makes me laugh. It's like you're asking "Which old, rare, finicky sports car should I buy to drive only in bumper-to-bumper traffic at 20 mph?" Then all the discussion of the nuanced differences between the Lambo, the Ferrari & the Lotus.

If your criteria includes "speakers will sit horizontally atop two bookcases", your in room performance will be so compromised that the list of 6 issues seems really over the top. You need to setup most monitors on proper stands somewhat away from the wall behind them to get anywhere near their capabilities. 

OP's list of concerns indicates a fairly high bar of what he's hoping to achieve. Perhaps if lifestyle issues preclude proper setup, consider a nice set of headphones instead.  Sorry, not trying to be Debbie Downer, here. Cheers,
Spencer

OK. So you want a pair of 40+ year-old bookshelf speakers, installed high on bookshelves (with 31" vertical clearance) to fill a space almost the size of a 2-car garage, but NO SUBWOOFER.

Well, I think I almost have an answer. It may meet a lot of objections here, but for your purposes it should meet your visual and sonic requirements well.

With that size of a space, I doubt you’re looking for pinpoint imaging. You’d probably like a large soundstage so you have an even balance as you move about your studio.

So here’s my suggestion: Bose 901 direct/reflecting speakers. No need to buy used; they’re still in production and look pretty much as retro as the originals. It also means a factory warranty and all the parts are available and in production.

But for these to work right you’ll need to fudge a little on your placement ideas while not violating the general idea of keeping them up and out of the way. The 901s have eight rear-firing 4.5" drivers and a small port. There has to be at least 12" between the back of the speaker and the wall behind it. Two or three feet might be better. Setting them on the top of your bookshelves leave no space between the back of the speakers and the wall, but you could hang them from the ceiling on cables or chains, at the same height as if they were on top of the bookshelf, and about 1-2 feet in front of the wall behind.

Bring a lot of power to the party--150-250 wpc preferred. They will play a wide variety of music well. They will fill your space pretty effortlessly, and with a high current powerful amp, you’ll have fast, tight bass. You’ll also get a stable soundstage and pretty uniform volume and timbre response throughout your studio.

Tone Publications did this review of the 901s, listening to them without prejudice, and flew in the face of long-running audiophile sentiment with a very favorable review, especially at their asking price of $1395/pair.