The Yugo should be able to handle 308. A lot of Yugo rifles were turned into 308 rifles.
I have a questions are these rifles in their original stocks? If they are by the time you find stocks, barrels, chamber reamers and head space gauges you could buy several hundred rounds of box style brass in 8MM, reload it yourself. The days of cheap rifles like mauser's seems to be over and a lot of these rifles have been sporterized. So a rifle in its original stock even if numbers arent matching will have a value someday.
Plus sometimes when you replace barrels you can damage a receiver