If you charge/balance the cells they will be fine depending how old the original pack is.
Speaking from personal experience, it's alot of trouble. I had to replace 5 cells and any more then it was better to buy a complete new pack. So have a big think if you just want to pull apart the pack and use the old cells for other things. That might be better.
Ginge unfortunately posted the wrong link, please be very wary of inferior batteries - you need the 'orange' color at least, because the blue cased cells are generally always from lower rate batches too
(no offence mate!)
The link you want is
this one and make sure if you order them to select 'with battery tab' so you can cut the tab to fit in-line with the GM pack to squeeze it back into the casing
Looking back on it, I would still go with Gonzo's advice.....