Check w Pilkingtons, I'm pretty sure that someone makes/made a kit to lengthen the LoP of the Junior to be similar to the full size rifle. Actually it was for the P70-jr, but the butt of the stock is the same.
BTW, I shoot the P-70-jr, and in my case, the LoP fits me just fine.
As was mentioned, package the front and rear sight and DO NOT LOOSE THEM. I've seen too many FWB-300 where the owner scoped the rifle, and when it came time to sell...they can't find the sight. That could make a BIG DENT in the resale value, as the sights are expensive to replace.
What are you going to shoot w a scope w that much magnification?
Or are you going to do like me, to see how small a target you can hit :-)
N-joy the new toy