E-Lander Mags does not provide specific dimensions for their 10 round 6.8 SPC Magazine. I'd recommend contacting them directly for more information.
Yes, it will.
There is a small difference in the follower. This should still work, but you can find 10 round magazines for 6.5 Grendel on the following pages:
https://www.opticsplanet.com/c-products-defense-cpd-magazine-ar15-6-5-grendel-10rd-blackened-stainless-steel.html?_iv_magazine-capacity=10-rounds
https://www.opticsplanet.com/alexander-arms-alexander-magazine-6-5-grendel-10-rounds-steel.html
https://www.opticsplanet.com/cmmg-inc-ar15-6-5-grendel-10rd-magazine.html
https://www.opticsplanet.com/franklin-armory-dfm-magazine.html?_iv_caliber-193146313=6-dot-5-grendel
This should still work, but you can find 10 round magazines for 6.5 Grendel on the following pages:
https://www.opticsplanet.com/c-products-defense-cpd-magazine-ar15-6-5-grendel-10rd-blackened-stainless-steel.html?_iv_magazine-capacity=10-rounds
https://www.opticsplanet.com/alexander-arms-alexander-magazine-6-5-grendel-10-rounds-steel.html
https://www.opticsplanet.com/cmmg-inc-ar15-6-5-grendel-10rd-magazine.html
https://www.opticsplanet.com/franklin-armory-dfm-magazine.html?_iv_caliber-193146313=6-dot-5-grendel