It is just the action without the thumb cut, yes.
The HVA action is far superior to the 95/96 actions, IMO. They are a 98 Mauser design and made from far more modern steels. The several I've owned were very nicely machined and had good adjustable factory triggers. The ones sold by Simpson are probably mostly early ones with the steel bottom metal, weighing 44 ounces. The triggers are standard simple Mauser 98 type affairs. The later HVA action weighs in at about 40 ounces with alloy bottom metal.
Unless you plan to speed-lock the 95 action, the HVA has a much faster lock time with 1/2 the travel of 95/96. Except for 95s better gas venting, I don't see one other advantage it has and do see some drawbacks. With the HVA all one would need to do to have a very fine rifle is to screw on a good barrel and install a decent adjustable trigger.
I use mine in 7X57AI almost as much as my old 30-06 Winchester.
As to scope mounting, use Weaver 46/front and 55/rear. I have a Redfield JR-HC on my later HVA 7x57AI.
