Questions about HPD/Showa suspension

I’m concerned about purchasing “new-old” stock when it comes to these shocks as I would like for these to be reliable long-term. Has anyone purchased this suspension semi-recently and, if so, what are your thoughts?

Also, where should I source these shocks and springs from? I’ve looked at the forums a bit but, only a few answers over there. Anything else I should know before proceeding with this purchase? Extra parts, installation special procedures?

Thanks in advance <3