Flashing window in concrete cutout

Hello,
I'm installing a wood window in a basement where the wood frame cripple walls are about 3.5' tall. To maximize window height I cut out a 1' tall section of the foundation, and the window will sit in the cutout on a PT 2x6 sill plate. What is the proper flashing detail for the bottom of this opening?
Further details: The sides of the opening also have 2x6 PT trimmer studs. Because of overpour the exterior face of the foundation at the bottom of the cutout projects about 1.75" past the outer edge of the PT sill. I have made a redwood window sill which will sit on the PT sill with a 1/2" rabbet and project 2.75" past the outer edge of the sill. This leaves a 1" gap between the underside of the redwood window sill and the top of the concrete. The window itself is just a box which sits on the redwood window sill, there is no nailing flange.
A scale ASCII art cross-section is below.
Thanks, Wayne
CROSS SECTION
S = redwood window sill, cut from 2x4 M = 2x6 PT sill B = 2x6 PT side buck or trimmer stud C = concrete
Scale: XX = 1/2" square
~ ~ B B B B 12" up to adjoining mudsill B B B B B SSSSSSSSSS B SSSSSSSSSSSSSSS MMMMMMMMMMMMMMMMMMMMMM SSSSSSSSSS M M MMMMMMMMMMMMMMMMMMMMMM ~CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC C C 8" down to grade C ~
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http://www.bakor.com/airbarriers_literature.asp
Have a look at the BLUESKIN SA and TWF
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