(1) Montana No. 1 shall be equivalent to U.S. No. 1 with the exception of tolerances for defects en route or at destination. Montana No. 1 shall allow 24 percent for cherries in any lot which fail to meet the requirements of this grade: PROVIDED, that included in this amount not more than the following percentages shall be allowed for defects listed:
(a) eight percent for cherries which fail to meet the requirements for this grade because of permanent defects; or
(b) six percent for cherries which are seriously damaged, including therein not more than four percent for cherries which are seriously damaged by permanent defects and not more than two percent for cherries which are affected by decay.