727 clutch pack clearance

I have not built a lot of TFs but my rule of thumb has always been minimum .010 per friction. More is ok, but I have never installed looser than .015 per friction.

As for me, I would hunt up different frictions to better get into the ball-park. I have mixed and matched with no issues.
And I have also reused many many good frictions.

My test to proove the frictions is to push a small screwdriver along the surface (about a tip size of 1/8, and on the flat), slightly tipped up to attempt to dig a groove.. If carbon material chips off leaving a groove, it has been baked and is junk. If it leaves a trail of dry still-bonded material behind it, and only oil ahead of it, then it is reuseable. There is no in-between.
If you suspect your test is lying, then dig a corner in and drag backwards; if it leaves chipped up carbon material and a groove, it's junk.
You don't have to be rough, and if you do and it still passes, don't worry about a mild groove as long as NO carbon chipped up.