I would call Jim at Racer Brown. He will explain it better. But LSA and ICL are a function of other parameters.
It also follows the line of thinking that a 6.123 rod is a "long" rod. It is if the stroke is 3.313 then it's a long rod, relatively. But if you have a 4 inch stroke, the rod isn't so long. So really, what is a narrow LSA and what is a wide LSA? It's relative.
As to intake centerline, I am way old school. This bullshit marketing ploy that Comp devised decades ago to install everything 4* ahead is just that. Bullshit marketing. The reason for using 1 or 2 degrees of advance was to compensate for timing chain stretch. The cam will retard under load and chain wear. Then Comp pulled a marketing scam.
The intake centerline is just that. Where the intake is at max lift, after TDC. If you have to advance a cam more than 1-2 degrees to compensate for timing chain stretch, you have the wrong events to start with, and you are leaving power on the table.
All that said, heads with crappy exhaust ports and great low lift flow, will get hurt with a narrower LSA, and then the cam guy will advance the ICL to fix it. You should fix the head. Set your valve job to stop reversion. Reversion causes rough idle and makes the fuel curve rich. Think about it. The air goes through the booster 3 times!!!!!! That gives you 200% more fuel than you want. That really isn't an LSA or ICL issue, it's a port/valve job/chamber issue. So the cam guys, instead of educating the customer on air flow and such, they make the LSA wider and set the ICL earlier. Power right down the toilet (or port as it may be).