I'm in the process of getting my dad's old model 99 back into working condition. Several years ago I ordered the feed throat conversion for it. Just getting around to installing it but having an issue. The spring that came with it seems to short to hook into the hole & even when I get it in the feed throat acts like it's too tall. I can,t get it to bolt in. Does the bolt also have to be changed when doing the conversion & can I use the stock spring & lifter with the new style throat?