*It is assumed LJ1 was the 454 replacement for the 427 Tri-power, 400hp L68. This is logical because a '70 Corvette assembly manual shows a 400hp LJ1 engine getting the same M40A Hydramatic transmission as the 390hp LS5, thereby classifying both on the lower performance end of hydraulic lifter big-block engines. Looking at RPO codes for 454 engines, it becomes obvious the slot for LJ1 is right after LS5. Mike Mueller, in his book Classic Corvette-The First 30 Years, mentions the possibility that the LJ2 was the 454 equivalent of the 427 L89 engine, which would make the LJ1 the 454 equivalent of the L71. However, I don't think this is a likely scenario because aluminum heads were not a popular option, and the trend at GM was to get rid of costly low production options. All considerations point to LJ1 as the 454 replacement engine for the L68 and the LJ2 as the equivalent of the L71. I believe Mueller agrees with this, as he refers to the LJ2 as the tri-carb L71 replacement various times, with the possibility of an L89/LJ2 connection only once.
Early Corvette Big-Block Engines - True Power
Just How Powerful Were Corvette's Early Big-Blocks?