Noah's probably a little low because these numbers start in 1978. He doesn't make the top 10 in the other list built from 1969, so I don't think its far from the mark. Again Guadio got a huge bump from beating Coria and winning in 2004. The ELOs are actually very tightly bunched except for Federer, but that is misleading since these are 2012 and back. 2015 and back top ten again for easy reference:
On clay these ratings have Borg at 2:
Player Year Clay Ct Elo
Rafael Nadal 2009 2550
Bjorn Borg 1982 2475
Novak Djokovic 2015 2421
Ivan Lendl 1988 2408
Mats Wilander 1984 2386
Roger Federer 2009 2343
Jose Luis Clerc 1981 2318
Guillermo Vilas 1982 2316
Thomas Muster 1996 2313
Jimmy Connors 1980 2307
Fed has a little seperation, but the top 5 clearly seperate. I prefer to guestimate the older codgers and Djoker in with the slam weighted rankings:
Pos Name Ratings Date
1 Rafael Nadal 3142.25 May 18, 2009
Bjorn Borg 1982 ~3020
Novak Djokovic 2015 ~3000
2 Roger Federer 2953.74 September 21, 2009
3 Ivan Lendl 2879.27 May 30, 1988
XXXXX 4 Novak Djokovic 2807.51 May 30, 2011
5 Mats Wilander 2800.23 September 23, 1985
6 Gustavo Kuerten 2794.66 July 23, 2001
Jose Luis Clerc 1981 ~2793
Guillermo Vilas 1982 ~2793
7 Thomas Muster 2792.64 June 26, 1995
Jimmy Connors ~2780
8 Juan Carlos Ferrero 2777.80 July 28, 2003
9 Sergi Bruguera 2775.01 July 12, 1993
10 Jim Courier 2768.41 June 1, 1992
Yannick Noah ~2766.26 April 23, 1984 (adjusted too 15 with the older codgers thrown in and just ahead of Soderling.

)
Kuerten is quite respectable on this list with ELO and I like that.
For Noah, I'd say he's hurt some in the slam weighted ratings as you say, but still doesn't make top ten. His rating is surely a tad low. Another 30 points and he's in there with Courier and Soderling. For rating the fields this is not going to blow anything up too badly. It might be better if these ELO numbers were rounded to the nearest 25 or something and players shown as ties for rankings. 100 points is a significant gap when you do odds on current matches, 200 a wide gap, and 400 an ocean apart. I'm not too worried about Guadio being overrated, because he won't affect my field rating unless he makes the QF. I'd love to correct
I guess I need to do the French Open next.

Keep talking about clay all you want here that will just spur me on. I think the field ratings for clay will be very interesting and I'd like to do more guestimates if we have the knowledge.
I have all the data, I wish I had the know how and technology to maintain surface specific ELOs.

I have a friend who's worked with databases a lot in the past. I may ask him about the feasibility. I'd just like to read in the PDFs monthly and click a button to calculate the current ratings. Put in a time in the past and calculate ratings with the click of a button. That would be incredibly cool. It may take a computer program to accomplish. Not even sure if VBA code with Excel and access would be up to the task. If someone had the data for pre open era that would be a laugh riot to try with players moving into the pros from amateurs. ELO is the only number or ranking that would have a prayer of negotiating the "amateur" era.