With a dual master cylinder installed your freeplay may be different from stock. As mentioned above, the plunger has to move into position to relieve the pressure. I'd think 1/8" is too tight even with a stock MC.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.