Hi,

See
1. The Vedic Buddha Date
http://www.vnn.org/editorials/ET0003/ET14-5679.html

See also:
http://www.geocities.com/narenp/history/info/epilogue.htm
http://www.geocities.com/~ramayanam/india_history.htm

2. Reestablishing the Date of Lord Buddha
by Stephen Knapp
http://www.stephen-knapp.com/reestablishing_the_date_of_buddha.htm

3. The Date of the Buddha
http://www.umass.edu/wsp/conferences/lectures/buddha.html

4. The Date of the Historical Sakyamuni Buddha
edited by A.K. Narain
https://www.vedamsbooks.com/no31325.htm

5. When Did The Buddha Live? : The Controversy on the Dating of the
Historical Buddha--Selected Papers Based on a Symposium held under
the Auspices of the Academy of Sciences in Gottingen/edited by Heinz
Bechert. 1995, 387 p.,
https://www.vedamsbooks.com/10723.htm

6. The Dating of the Historical Buddha:A Review Article
L. S. COUSINS
http://www.ucl.ac.uk/~ucgadkw/position/buddha/buddha.html

7. There is also an article, but the link has expired. Go to
google.com, type "Buddha 788 BC"

The text from that website:

The distance from the start of the Ascending Passageway to the
fourth Girdle Stone (of Buddha) is 1069.86801156 P". When you
subtract this from the fourth Overlay (of Buddha), 1856.77471784 P" -
1069.86801156 P", you get 786.906706285 P", or August 12th, 788
B.C., the date for the Advent of Buddha. (see Figure 14)