I never actually put my 968 in one, I have a 268 in there currently. I did put them side by side prior to install and after I killed my 968, fit looks to be very very tight. The stated specs of the shield says 4.4" inner height. The 968 measures out at 4.23"s But that is assuming no cable coming out of the bottom. I think you can modify the 968 since it will be in the shield (take outer sheath off), or just cram it in there. However might be worth the extra 5 bucks to get the LX shield.
You probably only need one extra plate, but LX comes with two more. Or, you could try the regular one, then order the expansion kit later for $5, but then you will get ups'd on shipping.
Andrew