I bought my 742 .30-06 back in the very early 1980s. For years I had inexpensive aluminum see through mounts; they were awkward and unattractive. The screws wouldn't stay tight even with Loctite.
Last year I ordered some steel Leupold mounts for the 742 from Midway. They are far superior to what I had, and look better (to me anyway.) The Leupold 742 steel mounts are NOT interchangeable with the 7400.
Having said that I am not a 742 fan. The gun groups poorly (~3") unless I let the barrel cool all the way down to COLD between shots. The best ammo I have found for it is Remington 180 grain Core Lokts; my handloads didn't really do any better, and I seldom use this rifle anymore after buying a few bolt actions to hunt with. With
much patience between shots and the 180 grain Remmies I did get some four shot groups just over an inch, so if I make my first shot count I've got a reasonable chance of hitting where I want. Still, unless I need a quick follow up shot (such as hunting hogs in brush) I prefer my bolt rifles.
I have never had a jam with my rifle, but I tend to keep it clean. One thing to be careful of - - parts for the 742 can be hard to come by, and if the gun is too worn it may be beyond economical repair. You might want a gunsmith to look at it.
All in all, if you are looking for exceptional accuracy, you're probably going to be disappointed. You'd be better off with a bolt action rifle. If you are looking for a reasonably serviceable hunting rifle for <150 yard shots then you'll be ok as long as the gun has been well cared for and not worn out. The gas operated semiauto action does reduce felt recoil a bit. My guess is that you will like it a bit better than your Marlin .30-30; that was what I had before I got the 742!
Good luck - - post a range report when you get a chance to take it out!