I've not hunt either of those much, but if I had to go with one 12-gauge load for both, I would probably use 1-ounce of #7 1/2 lead. It is my understanding that for some late season grouse hunting you might want to go with a little heavier load like a 1 1/8-ounce of #6 lead.
As far as chokes are concerned, a Cyl, SK, or IC will probably be your best choices since this is normally a close range affair.
Here are a few of my pattern numbers from some woodcock/grouse appropriate loads that will give you an idea of the kind of performance you might get with different chokes.
Patterning results from a 12-gauge Browning Citori with 28" Invector-plus barrels using Briley flush chokes (patterns average of five, 30" post-shot scribed circle, yardage taped muzzle to target, and in-shell pellet count average of five).
30 YARDS / CYL
Win AA XL 2 ¾” 1 oz #8 lead (393 pellets) / pattern 218 (55%)
Win AA XL 2 ¾” 1 oz #7 ½ lead (344 pellets) / pattern 194 (56%)
Reload 2 ¾” 1 1/8 oz #6 lead (267 pellets) / pattern 147 (55%)
30 YARDS / SK
Win AA XL 2 ¾” 1 oz #8 lead (393 pellets) / pattern 256 (65%)
Win AA XL 2 ¾” 1 oz #7 ½ lead (344 pellets) / pattern 248 (72%)
Reload 2 ¾” 1 1/8 oz #6 lead (267 pellets) / pattern 171 (64%)
30 YARDS / IC
Win AA XL 2 ¾” 1 oz #8 lead (393 pellets) / pattern 305 (78%)
Win AA XL 2 ¾” 1 oz #7 ½ lead (344 pellets) / pattern 288 (84%)
Reload 2 ¾” 1 1/8 oz #6 lead (267 pellets) / pattern 211 (79%)
40 YARDS / LM
Win AA XL 2 ¾” 1 oz #8 lead (393 pellets) / pattern 251 (64%)
Win AA XL 2 ¾” 1 oz #7 ½ lead (344 pellets) / pattern 260 (76%)
Reload 2 ¾” 1 1/8 oz #6 lead (267 pellets) / pattern 173 (65%)
40 YARDS / M
Win AA XL 2 ¾” 1 oz #8 lead (393 pellets) / pattern 292 (74%)
Win AA XL 2 ¾” 1 oz #7 ½ lead (344 pellets) / pattern 272 (79%)
Reload 2 ¾” 1 1/8 oz #6 lead (267 pellets) / pattern 182 (68%)
Good luck!
PS: Sorry, had to correct an error on the LM choke #6 load percentage from 75 to 65%, it makes a little more sense now!