At least up to 71, here's how GM lists them:
L22 L-6 Engine - 250 Cu. Inch.
L26 L-6 Engine - 230 Cu. In.
L30 V-8 Engine - 327 Cu. In.
L34 V-8 Engine - 396 Cu. In. Hi-Perf.
L35 V-8 Engine - 396 Cu. In.
L36 V-8 Engine - 427 Cu. In. Hi-Perf.
L46 V-8 Engine - 350 Cu. In.
L48 V-8 Engine - 350 Cu. In.
L62 P-6 Engine - Hi-Perf.
L63 P-6 Engine - Spec. Hi-Perf.
L65 V-8 Engine - 350 Cu. In. (2 Bbl. carb.)
L66 V-8 Engine - 396 Cu. In. (2 Bbl. Carb.)
L68 V-8 Engine - 427 Cu. In. - Hi-Perf. - Tri Carb.
L71 V-8 Engine - 427 Cu. In. - Spec. Hi-Perf. - Tri Carb.
L72 V-8 Engine - 427 Cu. In. - Spec. Hi-Perf.
L73 V-8 Engine - 396 Cu. In. - Spec. Hi-Perf.
L78 V-8 Engine - 396 Cu. In. - Spec. Hi-Perf.
L79 V-8 Engine - 327 Cu. IN. - LD - Spec. Hi-Perf. (Hyd. Lifters)
L85 L-6 Engine - 250 Cu. In. (4 Bbl Carburetor)
L87 P-6 Turbo Charged Engine
L88 V-8 Engine - 427 Cu. In. Heavy Duty
L89 Aluminum Cylinder Heads
LF7 V-8 Engine - 327 Cu. In. (2 Bbl Carb.) (Reg. Fuel)
LM1 V-8 Engine - 350 Cu. In. (4 Bbl Carb.) (Reg. Fuel)
LS1 V-8 Engine - 427 Cu. In. (4 Bbl Carb.) (Reg. Fuel)
LS3 V-8 Engine 400 Cu. In. 4 Bbl. Carb.
LS4 V-8 Engine 454 Cu. In. 4 Bbl. Carb.
LS5 V-8 Engine 454 Cu. In. 4 Bbl. Carb. Hi-Perf.
LS6 V-8 Engine 454 Cu. In. 4 Bbl. Carb. Spec. Hi-Perf.
LS7 V-8 Engine 454 Cu. In. 4 Bbl. Carb. Heavy Duty
LT1 V-8 Engine 350 Cu. In. Special High Performance
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Dale McIntosh
TC Gold #92/ACES #1709
67SS & 67 Elky
Dale's Place
Team 67