Recommend a 5/16 tsc drill to go over 8" deep?

I have a family of parts that I am looking at doing made from primarily 6061t6, they have quite a few 5/16" holes going from 5-8.125" deep.

I would be running this job on 15k rpm hmc with 400psi tsc. I don't really have much experience going more then 12xd, so these parts at 26xd are new territory for me.

I am wondering if there are straight flute gun drills I can get to do the job, and if 400psi is enough to evacuate chips.

If so, what drill do you recommend?

Thanks!