Don't sweat over x25 to x30 that's just how many mm long.
25mm is 1", where 30mm is just under 1-1/4". It's all close enough to x28. You'll get away with 1" bolts on the cross member bolt holes. The holes don't go through and through the hollow member so if your bolt is more than 1-1/2" you may run into the top steel in there.
Also important: Keep in mind those Metric bolts are fine thread - look for 1.25 pitch. (Standard out there is 1.5 pitch).
Pretty much all those bolt-on spots on the cross members under the body are M10x28 x1.25 pitch. Those holding the tow hook are M10x50 x1.25 pitch. (I don't know about you guys, but it was a bugger to find 1.25 pitch bolt longer than 2.5" in my town. Everyone had 2" long, but I needed that extra bit for my skid and tow hook bolts. Eventually lucked out.)
I would definitely take marlins advice and buy a M10 tap and ream those rusty bolt holes, they're nasty when they plug up with gunk.