I think there are some monthly completed totals for '66 and '67's and they varied, as might be expected, based on beginning of the production series and parts to complete on-hand.
Seem to remember reading articles in The Shelby American referencing production meeting notes on Hertz cars completions.
Review of the 2011 SAAC '67 registry would probably be able to provide a good/close total by month as it lists the Shelby completed dates of the cars.
Will look... found these monthly totals that someone gathered (not me) on '67 Shelby's completed at the airport. Guessing they got these by reading the 2011 Registry, not sure of the accuracy:
1966 Oct = 21
Nov = 62
Dec = 89
1967 Jan = 267
Feb = 221
Mar = 460
Apr = 635 653
May = 588
Jun = 373
Jul = 459
Aug = 8
Sep = 5
Oct = 19
If April (the month of highest out-put) had 22 "working days" (30 days minus 8 weekend days) that equates to about 28 29.6 cars a day highest production month average per day.
Correction as per reply below - Thanks Dennis