First question- yes, a Super or Super Hunter frame will fit. But unless you can find one that has been factory installed, you have a bit of a job ahead of you. I fit a Super Hunter replacement grip frame yesterday, and it takes a couple hours of sanding and polishing, and a lot of elbow grease. A word of advice- if you buy one from Midway/Brownells- try it on the main frame first. I have had issues with the Super Hunter frames being machined a bit off center from the factory. Ruger customer service said they would fit a Super frame to a New Vaquero for me, but I wanted to do it myself. The raw replacement frames are around $130 if i remember correctly.
Another option is a grip frame from RW Gripframes. Ronnie makes multiple styles including Super Blackhawk with multiple trigger guard styles, hammer openings, and even an extended frame for big hands. Ronnie's frames only come in brass $350 or aluminum $300. He offers grip panels too. Last time I checked he would fit the frame to your gun for about $150.
Or…get the 7 1/2", and have Fermin Garza shorten the barrel to your preference and install one of his excellent front sights. That way you get the grip frame you want, the non-fluted cylinder, and a great front sight!
