frame tabs and body dilema

[old Rusty C10]

yesterday i posted a thread and i did get one answer from Capt Kaos and i need to re ask this in a new way.
I have a 1976 C10 which has a bad body and bad body mount tabs for the front mounts.
I have a 1985 cab which is in good shape
and i have a 1981 C20 frame which the cab i have was originally mounted to
what i want to know now is if i take off the tabs on the 81 and bolt them to the 1976 will they fit right on the 76 chassis and then i could use the new style body mounts to put the cab to the front tabs and old style to the rear body mounts and my 85 cab would fit and mount to my 1976 frame with the 81 front cab mount tabs??