I'm not a very good handgun shooter. If I can keep a mag or cylinders worth of shots inside of 6" at 25 yards shooting freehand I'm pretty happy. Most handguns if shot from a rest can do about 2.5-3" at 25 yards regardless of barrel length.
Having shot SASS with revolvers from 3" barrels all the way to 9" I personally prefer 7.5" guns. I always shoot either duelist or gunfighter style for those that are interested.
When I first started SASS I only had one legal shotgun (CZ hammered SxS) and I used full length brass hulls loaded with BP. I did not need to resize them. Of course I wasn't particularly fast, and the hulls did not smoothly shuck out either. Later on as I acquired more guns including more shotguns, I switched to plastic for both speed and convenience.
I might be alone on this one, but I load my cap guns exclusively with the supplied under the barrel load lever. If your cap gun is stock it comes with a host of gremlins inside. There is an excellent article written by Larson Pettifogger that address these issues. For starters the short arbor/barrel cylinder gap has to be fixed and the stock nipples should be replaced with some from either Treso or Slixs. A properly tuned and loaded cap gun will be reliable as a cartridge gun and easily run for a two day match without serious cleaning between stages. I highly recommend Mike Brackett's work on cap guns for anyone serious about shooting Frontiersman.
For my own edification, once a percussion gun has been converted to shoot cartridges how can they still be shipped/sold as a black powder firearm without an FFL? I'm not asking about the drop in conversion cylinders which allow you to switch back and forth. I am talking about the gated conversions that require permanent modification to the pistol.
The older Japanese made SKBs and Charles Daly model 500s are very high quality. The Browning BSS will also often be mentioned. Problem is all these guns have been long out of production. The current production SKBs and CZs are probably the best options for currently produced SxS. I've handled a few of the CZs Longhunter sells already slicked up, very nice guns for the money in my opinion.
Edit: Just checked Longhunter's website and it appears they are no longer selling already slicked up shotguns. That being said I would still consider the newer CZ a great base to start slicking up for SASS if an older Japanese SxS is not an option.
Short answer, YES you can use a Ruger Old Army with adjustable sights in SASS competitions. The Ruger OA with factory adjustable sights is legal in every category except for the categories that have specific fixed sight requirements for the pistols. Off hand I believe the categories that do require fixed sight revolvers are all the Frontier Cartridge ones, Frontiersman and Classic.
Like it or not the rail and other "tactical" features is very much the current convention for every major brand of lever actions currently being made. Heck even Uberti's website has an 1873 (both handgun and rifle) with a rail featured on their front page.
I don't disagree with you, but it sounds like the deal is already done and this guy has a S&W lever rifle.
The S&W looks almost exactly like a Henry rifle save for a few features that will be of no advantage in SASS. I don't see the issue if he wanted to use it at a monthly so long as it was explained it would not be allowed at an annual/state match and he would be ineligible for club awards.
While not legal for SASS, if this is your pard's only lever gun he could probably have it approved by your local MD for use at monthly matches. Who knows it might get him in the door and if he takes to it seriously he would be looking to upgrade to a rifle better suited to SASS anyways.