With the long LSN motors, depending on pipe and fuel I think you will find you will need to have the HSN just a hair in from flush on either motor to get a final race tune. Probably around an 1/8 to a 1/4 turn in, but certainly no more than 1/2 turn in or you will have problems. Start of with HSN flush and tune only with the LSN until you have good performance and good take off. You may find you are now just a fraction rich at the very top end. Now tweak the HSN as described to get the last quater of the rev range nice and clean.
Before you do anything, make sure your idle gap is set to .7 - 1 mm NO MORE. Otherwise you will chase your tale all day and end up with the situation where you have a way rich bottom end and a too lean top end. You will get a "false" idle due to the very rich bottom end and the wide idle gap. Motor will run sort of OK, but will get hotter and hotter as the tank drops. Another tell tale sign of this is the motor not returning to idle when you let the throttle off going over jumps. The revs will just hang there, making jumpng rather awkward.