Timing Chain Check

[Thomas]

I was hoping to finish the valve train installation on the 427 for my '69 Camaro SS this weekend.
I have a new cam, lifters, springs, locators, keepers and locks.

I was thinking of reusing the timing chain that was in the engine, as it is already a double roller (?) and the engine does not have many miles on it since the last rebuild in the early 80's.

I've measured the slack in chain at 0.345".

Is that too much?

The only reference I could find stated to replace it if it was 0.5" or greater.

Thanks in advance.