396ci/375hp motor with matching heads and aluminum intake.
T1207MQ 18N36 8 587
(fourth digit "8" between 6 and 5 is very faint, could be a 3, or 6?)
Casting numbers/dates:
Heads
GM3T 3919840 Hi Perf K 3 o 7
GM4T 3919840 Hi Perf A11 o 8
4 bolt Block
Truck Pass A Hi Perf 3916323 L4 o 7
Intake 3933163