for 1970:
If you have an original b'cast sheet (or Lynch Rd. fender tag) the 3-digit ENGINE number and 2-digit CARB number can be used to determine which engine is correct for a particular car.

383 manual - E & B-body - with ECS (N95)
orange HP engine 335hp
---------- Holley R4217-A ---------- part number 3418 537 on b'cast 37
383 manual - E & B-body - w/o ECS
orange HP engine 335hp engine on b'cast 084 with A/C & 087
---------- Holley R4367-A ---------- part number 3418 536 on b'cast 36
383 manual - E & B-body - w/o ECS & with "fresh air" (N96).
orange HP engine 335hp
---------- Holley R4736-1A ---------- part number 3512 964 on b'cast 64
383 manual - E & B-body - with ECS (N95) & with "fresh air" (N96).
orange HP engine 335hp
---------- Holley R4738-1A ---------- part number 3512 974 on b'cast 74

383 automatic - E, C & B-body - w/o A/C & w/o ECS
blue engine 330hp
---------- Carter 4736S ---------- part number 3418 538 on b'cast 38
383 automatic - E, C & B-body - with A/C (H51) & w/o ECS
blue engine 330hp
---------- Carter 4732S ---------- part number 3418 540 on b'cast 40
383 automatic - E, C & B-body - with ECS (N95)
blue engine 330hp
---------- Carter 4734S ---------- part number 3418 541 on b'cast 41

383 automatic - E & B-body - w/o A/C & w/o ECS
orange HP engine 335hp engine on b'cast 088
---------- Holley R4368-A ---------- part number 3418 542 on b'cast 42
383 automatic - E & B-body - w/o A/C & with "fresh air" (N96).
orange HP engine 335hp engine on b'cast 088
---------- Holley R4737-1A ---------- part number 3512 965 on b'cast 65
383 automatic - E & B-body - with ECS (N95)
orange HP engine 335hp
---------- Holley R4218-A ---------- part number 3418 543 on b'cast 43
383 automatic - E & B-body - with A/C (H51) & w/o ECS
orange HP engine 335hp engine on b'cast 089
---------- Holley R4369-A ---------- part number 3418 562 on b'cast 62
383 automatic - E & B-body - with ECS (N95) & with "fresh air" (N96).
orange HP engine 335hp
---------- Holley R4739-1A ---------- part number 3512 975 on b'cast 75