MA means it is a 58-64 truck 283 with 2bbl and auto trans.
OR
67-68 Camaro manual trans 2bbl 327

From the partial vin, the second digit is an 8 so it suggests 1968
so it was originally a 327 block.

The L267 decodes as being cast (not machined) on Dec 26, 1967 (L is december)