Hello. Welcome to Just Answer.
I am not a lighting specialist, and I don't think Just Answer has a lighting specialist. However, I would still like to offer my professional opinion.
I've been doing electrical work full time for about 20 years. I recently took a job at a new hospital, in the maintenance department. We have a few LED light fixtures on poles, in a parking lot that was added shortly after the hospital opened (about 3 years ago).
No one has said they like the LED fixtures. That particular parking lot is always darker than all of the others.
I am all for saving energy, but I really doubt you'll be happy with the light output from LED fixtures.
I should note that the LED fixtures were retrofitted, with original HID fixtures being gutted and replaced with LED components.
Even knowing that, I still don't think I could recommend the LED fixtures, just based on the difference in lumens you noted in your original question.
If I were bidding it, I would go with the tried and true HID fixtures, pulse start.
With those, you can KNOW you'll get the light output your customer is looking for.
Thank you for adding credence to my own hesitation with jumping on the LED band wagon. However, my customer is very pro-LED. Therefore, in light of what I already know combined with your thoughts on the subject, I feel better about taking a more rigorous approach to verifying the luminance capability of these fixtures. I plan to obtain reliable photo-metric diagrams, upping the number of fixture per pole if necessary, and outfitting each fixture arm with an adjustable knuckle type support fitting (to allow for directional adjustability).
Thanks for you candidness. The last time I checked your web site I noticed the areas of expertise have grown. Just Answer is a great concept. I hope your organization continues to expand into more subjects and specialized areas. It's really difficult to get straight answers these days that are honest, sincere, and credible.