Twenty years ago, I was building my "dream" rifle. I had an FN Supreme 98 Mauser in .30-06 converted to .308.
It took the gunsmith 8 months of work, on and off, to get it to feed right.
First, he had to solder shoulder rails inside of the magazine box, so that that they would hold the loaded .308 rounds against the back of the box, instead of sliding forward under recoil and getting out of kilter. Then he had to keep bending and rebending the metal of the box and the feed lips to get it to feed right.
He finally got it to feed flawlessly, but taking it back and forth to the gunsmith, and his very overt frustration and anger at the project, ruined the whole experience for me.
Here is my advice: Take your time, and keep checking the gun auction sites (G-broker) until you find a commercial FN 98 Mauser in .308 Winchester, such as the FN Supreme, the Sears J.C. Higgins, or the Interarms Mark X. These are high quality rifles, that have a built in "block" in the box magazine so that the .308 rounds will not jam, and they feed to perfection. You may also find a Husqvarna, although this is an upgraded Mauser 96 design.
Yes, these rifles will cost you some money, but they will appreciate in value, and you will happy with them from the get-go. If you sell your Yugo, and add to that cash the cash that you will have to spend on rebarreling and follow-up work, then you should have the $550 or so that it would cost you to buy a Mark X, which is the least expensive of the choices but still an excellent rifle.
Modifying any military 98 to a shorter caliber is a total crap-shoot, and can be very unsatisfactory, expensive, and sometimes you end up with a rifle that will NEVER feed right. And, if you get it to work, then what? You have an altered military 98 with crummy sights, no scope mounts, no altered bolt handle, and a lousy safety. Yes, you can fix all of that, for about another $200 to $400, and you may end up with a rifle that shoots 6 inch groups. Then what?
Another alternative? Take the money you are going to spend on the .308 conversion, and just go buy an entire case or two of high quality 8mm Mauser ammo. Then, every time you load your rifle, just "pretend" it is a .308. The 8mm is an excellent round in and of itself. If you decide to sell the rifle later, you will get all of your money back on the unaltered M-48 rifle and the spare ammo.
Hope this helps your analysis.