It will make a difference in stiffness, a little firmer dampening. A good radial tire with a higher aspect ratio will make it ride less harsh too. Say a 75 or 80 series versus a 70 or 60 series sidewall height. Correct tire pressure for the new weight distribution will also help the ride. You’ll have to experiment with that. I started with 18 lbs up front on a P165x80-15 radial tire on my VW based TD.
The slightly stiffer dampening will be slightly more noticeable in the front (lighter weight) than the rear.
The JC Whitney shocks I bought were not gas charged and cost me about $8.00 each back when I bought them.
I think there are only two major shock manufacturers (Monroe & Gabriel) in the US and they make all the “store brand” and “off'” brands sold here. Premium performance shocks like Bilstein and Koni are made overseas.
Maybe they don’t make “non-gas” shocks for this application anymore. Go with the Monroe’s if you can’t find an “off” or “store brand” non-gas charged shock locally. The change you made to the spring rate will make such a difference, you’ll be too happy to notice the dampening! LOL!!!