Getting a new bike '78 CB550

In the next few days I'm going over to look at a bike that a co-worker has for sale. 

He told me it idles hard and stalls out after warming up.  Explained he drove it around the block and it died out and wouldn't start and he had to push it back to his garage.  After it cooled off it would start again.

Any advice on what to ask or look for prior to buying it?  I don't mind doing some work to it but would rather not have to rebuild an engine

Thanks to anyone in advance.