I found this with my Win 70 Safari Express as well.
I think the stock designers of these bolt action rifles (even in DG calibres) view the irons as 'back ups' at best, aesthetic elements at worse and design the best possible stock to perform with a low power optic instead.
I wouldn't necessarily disagree with this view (after all, you probably are going to put a straight tube scope or a red dot on it), but it does mean that the comb tends to be a little high for the irons.
I'd point out that I'm no stock fitter, but again defending this position, I do think there has to be a compromise somewhere, it's just if you're compromising the fit with scope more, or the fit with the irons.
That being the case, I'd say that your options are to either adjust the stock so it's perfect for the iron sights (but possibly at a cost of a less perfect cheek weld with the scope you'll fit), or leave it as it is, have it perfect with the scope and accept that it'll be useable, if a bit suboptimal with the irons.
I ended up leaving mine as is on the assumption that more of my shooting was with the scope and that if I ever needed the irons, I could live with mashing my face down on the comb a bit for a couple shots. I also found I got to used to that stock shape over time and must have shifted my technique to accomodate, as I was perfectly able to practice with the irons after a couple months without bruising my cheekbone anymore.
The other option might be to accept that the stock is as it is, but look instead to change the irons to more closely mirror the head up positioning seen with a scope. Perhaps also think about swapping the irons for a peep site of some kind which sits a little higher?
I guess none of this actually answers your question (go figure!), but it might be useful food for thought. I would say that I'd agree with Tanks that it's unlikely to be as simple as just extending the LOP, although if your cheekpiece slopes down towards the back of the stock so that if your cheek moves back it ends up lower down then it might help I suppose?