It would definitely have to be near the corner since the 214d~~c has to be early. You can pick up Tager again with 5c after Jakou mid-screen, but the Jayoku after 5c would launch them horizontally enough where you would need to dash to connect 214d~~c, not allowing you to do it early enough for the height you need for the remainder of the combo. When I get home I'll test this and if it works I'll record it and post a video.
Also, think about adding 6c CH to the beginning to make it:
6c CH, 5d-d, b+c (whiff), Jayoku, 6d-a x 3, 623d, 665c, Jayoku, (early) 214d~~c, 5c, 4d-a, 4d-d, #j.214b.
Alternatively:
6c CH, 5d-d, b+c (whiff), Jayoku, 6d-a x 3, 623d, 665c, Jayoku, (early) 214d~~c, 5c, 4d-a, 4d-a, 623d, Mizuchi.
If my math is right, it could do up to around 9k.
Ugh, so much theorizing. I'm a projectionist and I have to screen Twilight two more times before I can go home. Crappy movies make you do math.