I don't see any alternative than what was suggested loosening the brackets enough until they will hit the frame mount holes. Maybe once the insulators set on the frame mount correctly, tighten the bracket bolts before putting the full engine weight on them (or not tighten fully until trans is installed and tightened down)..
Are you considering the store bought insulators?
The mount you removed from the brackets are correct for 1954. I came across a 1955 LINC CHASSIS PARTS MANUAL.
The stamped steel frame mounts, how are they attached to the tubular cross-member?
You have the correct year WORKSHOP MANUAL?
And when you pulled the engine, the mount studs did not catch and cause the chassis to rise any?
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