I think that is about right – but perhaps a year or two earlier, with Wisden a little behind with its plans. I have always believed the stands’ construction (like so much else at the time) was financed by the Supporters’ Association football pool. Leslie Duckworth’s monumental history of the club published in 1974 suggests that the Association initiated a four-year plan of reconstruction in 1957, in readiness for the Ashes Test in 1961. This was to include “the reconstruction of the whole of the West Bank of the ground… at a cost of £60,000”.
I do recall that the seating in both stands originally extended to the rear with “infilling” with boxes occurring in the 80s as corporate hospitality (virtually unknown in 1961) began to assume its current prominence. Quaintly, Duckworth notes that the Press Box stand, completed in time for the WI Test in 1965, included “two private boxes which industrial concerns could book and reserve for their guests”.

It's also worth noting that according to the club website "No car parking will be available to purchase for our LV= Insurance County Championship and Royal London Cup fixtures." So members without season tickets will have to park on the street or perhaps at Canon Hill Park.