Some of the vendors you listed like Fastech will likely take a month to 45 days to get your product. Only use Paypal
Different color tints, like cool white, white, or high Color Rendering Index will have a different perceived lumen output by each persons eyes.
To complicate it even further: Tint, Binning, and CRI Explained (For XM-L LEDs)
How do you plan to shed heat with a sealed PVC container? 1K lumen out of any led is gonna get hot. For that reason alone, I would not want to overdrive things.
Also keep in mind that most lights are going to step down in output as they heat up and voltages drop. So you may have 1k lumen for 5 minutes, then 30 min later same light is putting out 500 and so on.
Just some non technical thoughts.