Yes, that's an AS toilet.
I have had great success with the Korky adjustable-height flush valve product on two of my older AS toilets. You don't have to cut the tube to the right height, the overflow riser is wider than most which can make it less likely that a spill occurs in the unlikely event that you have a runaway fill valve. It also comes with a Korky-plus flapper, a sponge gasket that worked great in my old AS toilets, and a decent set of mounting hardware, although it used a single nut setup (rubber washer under bolt head, thread bolt through tank and bowl, secure under bowl with metal washer and nut) rather than a double-nut setup (rubber washer under bolt head, thread bolt through tank, secure on outside of tank with one washer and nut, then thread bolt throgh bowl and secure under bowl with rubber washer, metal washer and nut, all in that order).
Here's the Korky product, available at Lowe's: http://korky.com/FlushValveKit4030PK.html
Korky invented the flapper in the first place, and is generally-regarded as making excellent flappers. They also make the fill valve used on many Toto toilets, and the universal replacement fill valve that Toto sells as an original-equipment part.
It also comes as model 4020PK without the sponge gasket and tank-to-bowl mounting hardware, and in the 4010PK Universal Toilet Repair Kit (for 2" flush valves, which yours has), which also includes a Korky 528 fill valve. I'd give you the link to Lowe's but their site is down at this hour. You can look around the Korky web site for instructions on the other versions, and the excellent directions.
Lowe's carrys a good selection of the Korky stuff; you can use the search term Korky on their web site to see; HD carries a much-smaller selection. Many local hardware stores, and chains like Ace, carry a decent selection of Korky stuff.
While the Korky setup worked fine for me, if I was just looking to replace the mounting hardware, I would probably go with a double-nut setup. Something like the Lasco 04-3675 may be quality-overkill, but you'll see the kind of thing that I'm talking about.