2400 Front Sight

Hi everyone! I am new to this site. Just purchased a Savage/Valmet 2400 in virtually mint condition. 12ga./.308. It is very accurate, not to mention beautiful. With the front sight that it comes with, I am dead-on with the bottom barrel (.308), but am shooting low with the upper 12ga. barrel. This is both with shot and Brenneke slugs. Now, I know I can adjust the bottom barrel, and not the top barrel. That means that the front sight has to be filed down in order to bring the POI up. However, I don't want to touch the sights as they are original and came with the gun. Do any of you folks know where I might be able to get a replacement front dovetail sight to be able to file down? I'd like to get both barrels shooting spot-on at about 50 yds. I am planning on putting a 1.5-5X scope in Sako quick detach mount/rings (Optilocks), as the receiver is designed to accept Sako mounts, but not for a while. At $450 for the quick detach set, it's a bit pricey. Anyway, I want to get the top barrel shooting to the sights, then adjust the bottom barrel to meet the top barrel at 50 yds. Any help you can give me in locating a front dovetail sight will be greatly appreciated.