Look Out Sir says that an unsaved wound that is allocated to a character, the wound can be re-assigned to another model in the unit if it's within 6" of the character (pg 16)
This is not the complete ruling.
Pg 16 Lookout sir states.
"When a Wound (or unsaved Wound) is Allocated to one of your characters, and there is another model from the same unit within 6", he's allowed a look out sir attempt."
So what you are asking is essentially can you choose to wait to trigger lookout sir until the ALLOCATED WOUND then becomes an UNSAVED WOUND after your
IC takes his/her save.
LOS triggers on 'allocation', so he could not roll saves and then use LOS; he would have missed the trigger.
I agree with coredump, however the language is ambigious.
On another note:
I have been seeing folks making the mistake that they can put their
IC closest and do mixed allocation even if all models in the unit (including
IC have the same save)
X*Edited to add my opinion.