Yes, your math is correct.
LS1 rocker puts the pushrod seat .040" lower than the AMC rocker from my '90. The AMC rocker ratio measured 1.605, LS rocker 1.715. That's just straight measuring the rocker, not the actual valve lift vs lobe lift measured with a test spring (my engine is still in pieces).
I'm going with the summit K8600 camshaft kit which as .080 smaller base circle on exhaust, .050 on the intake. So I may be able to reuse the factory pushrods on the exhaust and compress the lifter .015 more on the intake.
But the heads, deck were touched, different brand lifters, who knows how the head gasket thickness matches the oem, so I'll find out when I assemble.