Have talked to Lifeline in the past and they insist that the weld on spline and QR are supplied as a matched pair and weren't impressed when I asked if their spline manufacturing was so bad that they had to hand fettle everything. I replaced my original QR which had started out looser than it should be and had got worse with time, with a new one which just fitted, and no, I didn't cut the splines off the steering column and weld on the "matching" new spline.
I wouldn't be surprised if your new QR will fit the original spline with only the most minor of fettling. Might be worth giving things a clean up with contact cleaner then blueing up the splines and seeing where it is tight before starting in with the needle files?