There are a lot of parts interchangable between the Jonsered 530/670 and the similar sized huskies of the same era. Cranks,ignitions, covers and so on.The main difference was the Jonny-red had a rubber mounted carb so the cyl. and carb boot were different.
Some of the intake etc differences also exist between different models of each brand as I remember it - but I don't recall the full story.
Studying the IPLs (easily available at Barrets site) is a good start, at least for being able to ask more specific questions.
http://www.barrettsmallengine.com/parts.html