@edelbby, you have some really great classic and desirable gear, no doubt.
IMO you are out pacing your gear at a similar pace by looking at a once classic "high end" speaker. I've spent lots of time with the WP8, and it was much better than the 7. The 7 was harsh compered to the 8 to my ears.
I'd advise you to get into a speaker that you like rather than trying to match an era and work backwards by looking at resale comparisons.
You should find a speaker that you love driven by that McIntosh amp. Don't buy blind based on the reputation of a speaker without insight into the amp. Does that make sense? So... maybe look at Sonus Faber, Dynaudio, Devore, Verity Audio, or any other rec's here. Come on guys...
There's something called synergy and you typically start with a speaker and word in the direction of amp, pre, source, etc. I would never start with an amp and look for a speaker at your stage in the game. Maybe after you have some experience.
Hope this helps and doesn't confuse more.