The problem with the double roller replacement timing sets in that price range is they all use a cast cam gear which wears very fast. Within 3-5000 miles there will be a lots of chain stretch, and you cannot use a chain tensioner with a double roller. :frown:
The less expensive sets are even worse in their longevity. This is not an opinion, as I have installed and replaced hundreds of these Buick chain sets over the past 25 years.
You do have 2 other options, one like the Cloyes, and other brands of double roller sets that use a billet cam gear. The other option is a TA set less expensive than the double roller type which does use billet gears and a silent chain where you can use a tensioner.
As far as changing valve springs, with most of the stock replacements I have seen and experienced, it is a waste of time and $$$ unless you are upgrading for more performance. This is not a maintaince item like the chain.
If you are going to do mods in the future, that is the time to determine if to do it, and exactly which spring to choose.