A Herculean project, well done!
I like the way you 'weight' tournaments according to the Top two players entered, makes some sense back when there was less depth and 2-3 outstanding players per era.
The one area I have concerns about is the points allocation to the four majors. Today's generation know these as the pinnacle of our sport but it wasn't alway so. Since 1981, all four have been fielding consistently strong entries. Wimbledon and Forest Hills traditionally always have done. But the Australian and French were extremely weak, lacking either world class or substantial international entries from 1970-79 and from 1976-78 respectively (and probably prior to that at various times as some experts on here who know the pre-Open era better than I do) and shouldn't be awarded the same points as a major fielding the virtually all the top players.
I discussed all this when Graham initially posted his computer rankings.
Hats off to him for what was as you say a Herculean effort.
The main thrust behind this was to take the "subjective" element out in making each progressive round double the points etc. On the other hand as you say there were obvious disparities in the strengths of the Slams at times.
The pecking order until the 70s in terms of prestige was obviously Wimbledon, Forest Hills, RG and then the Australian. Generally Wimbledon was the strongest, the Australian the weakest but the French could at times be stronger than FH. However once you start any points differences at all well then your objectivity immediately goes out the window.
While it's a good idea to grade the events on the strength of those competing to me it doesn't seem right that when the top player retires they should not be removed completely, more debateable when they are injured.
For example, there couldn't be any A tournaments in 1955 since Maureen Connolly was out completely or in 1961 after Maria Bueno was out from May.
Also if the two top players are competing then if one beats the other they will get points for an A event even if there are no B players in the field - however, if there is only 1 A player then the next is a C if C happens to beat A they will only get points for a B tournament. Surely their achievement is no less?
Of course, you could argue round in circles.