I would suggest that you focus on sensitivity, more than size. Look for something with a minimum of 92-93db (with one watt of input). Because of your amp, I would not go below a stated impedance of 6 ohms (ideally, 8 ohms), and even then I would scour the interweb for info about the speaker's actual impedance curve (I've seen 8 ohm-rated speakers that drop below 4 ohms for a fairly large swath of frequencies). If the impedance curve is fairly benign, the higher sensitivity will help to offset the 2270's relatively poor power supply (and its corresponding difficulty with lower impedance loads).
Of course, it is true that you will have some difficulty finding small--cabinet speakers with high sensitivity (see Hoffman's Iron Law). But there are plenty of narrow "tower" speakers that have a footprint no larger than a bookshelf on a stand.
You could additionally offload your amp by purchasing a high-pass filter, thereby keeping the lowest frequencies (and their disproportionate power consumption) out of your Marantz amp. In this scenario, the subwoofer would be singularly responsible for those frequencies.
I understand your attachment to your 2270, but I would urge you to consider the earlier suggestions about using it as the front-end to a power amp rated to handle 4 ohm loads (something which can produce at least 45-50% more power into 4 ohms than into 8 ohms). By using the Marantz as a preamp, you should be able to keep most of its tonal characteristics, and you can hide the power amp, or place it to be unobtrusive. Heck, I think you can get a very, very capable power amp from Crown for about $300 and use it to drive just about any speakers you can think of.
This link might be of interest:
https://hydrogenaud.io/index.php?topic=115349.0
FWIW, I own a Crown XLS 1002 and have used it in several of my home systems just to see how it performs as a main amp...it is not quite on par with some of my "audiophile" amps, but is most assuredly not a step down when compared to many/most consumer-level amps/receivers. I normally use it to power a pair of subwoofers.
Good luck.
EDIT: All of us are assuming that a shortfall in power is causing your problem. I would be interested in knowing at what distance you are listening, and at what SPL do you notice the speakers becoming distorted? You can download a reasonably accurate SPL meter for your smartphone (free...I use SoundMeter). Your issue could be something other than clipping...specifically, a problem with your amp.
Also, as you noted, it may well be that your Elac speakers simply cannot go as loud as you want before compression distortion becomes an issue.
Use the dowloaded meter to determine the SPL at which the speakers start to distort. You really need to figure out the root cause of your problem before spending $ to fix it.
On a related note...what is the semsitivity and impedance rating of your previous speakers?
And one other question...are you still having feedback problems with your turntable? You raised that issue in another thread, but never replied to recommendations for addressing it.
