My rod is too short.

[red211]

Swapping the 63 to a disc brake set up off an 87 donor truck. Not doing power at this time so swapped a dual bowl disc drum non power mast cyl from a 71 c10. Got it at OReilleys, it is the same as the impala and such. Bolted it on but rod is short, adjusted out but still short. The flange on the master cylinder that sticks through firewall is shorter than the single that was on it by a good inch. I went back and We did some checking but all were shorter. I made a spacer that fit inside plunger and that fixed it but haven't seen anyone else with this issue. I know the old master is correct since I have had it since 1980 and it was 100% original when I got it from Grandpa. Anyone else had this?