Honda XR75 mechanical advance mechanism

Just throwing this out for discussion... and any advice from those that have dealt with this issue before... and have identified AND found the correct way to make sure these return springs and arms are set properly..

Picked up a 1973 XR75 engine to put into my latest project. Upon disassembly I noticed that the return springs had zero tension on the cam return arms ... I had also just purchased just a used magneto off ebay for my next XR75 project and upon checking it, same thing. The return arm springs on both magnetos just flopped around doing nadda....this, it seems, would result in almost full spark advance even upon just using the kickstarter??

Has anyone dealt with correcting this? Is it a non-issue?
At what RPM should full spark advance be achieved?

Once I get one of the engines assembled and running, I will use a tachometer and timing light to see how the timing advance reacts thru the RPM range...

Thanks all[/ATTACH]