i don't know how to tell which engine is which. i have an 81. it is the same basic engine as the early lt1's. the block is the same. the lt1's had 4 bolt mains. yours has 2 bolt mains. that doesn't matter at all for street driving. the cranks are the same . the lt1 crank is steel. the 81 is cast. again, no biggies for street driving. rods on the lt1 are harder than the 81. that doesn't matter for street driving either. pistons will be a higher compression piston than the 8, but will fit perfectly into the 81 block. the heads and cam are the big difference. they also will fit the 81 block. truth is. after all thes years the aftermarket engine parts are eons bette than th lt1 parts. a good set of heads and matching cam will bring your stock 81 to life. good intake carb and distributor also will be needed. if you got the right heads cam and intake system. you 81 will blow the old lt1 out of the water.
steve pastorino
