I have seen this toilet.
Many plumbers in here like the Fluidmaster 400A. No doubt about it.
Others, including Terry, often recommend the Korky 528. It's a little quieter. It's easier to install, and the moving parts (the rubber stuff that will wear out over time) are contained in a little cap (the size of a dollar coin) that you can just buy for a couple of bucks and replace when the time comes. You don't have to change the whole valve.
I have put the 528 in all seven toilets in our family home and am very happy with it.
Korky is also made in the USA, Wisconsin in particular. The Fluidmaster is hecho en Mexico.
There are a number of versions of the 528. Your older toilet requires a fixed 20% refill rate (20 percent of the water is diverted into the little rubber hose to refill the bowl). So you can use the basic white-cap 528, which has that fixed refill rate. It's available a lot of places, including Lowe's:
Here's a video from Korky on how to install the 528:
Let us know if you need any help, and let us know how it goes.