There was, and is, a lot of debate about how much better (or not) a linear tracker sounds than a swing-arm turntable, but I like them. Have several, but not the SL-7. They do indeed have less inner groove distortion if you can hear that -- my ears aren't good enough to notice much any more.
One thing strongly in your favor there though is that they are fully automatic and will save you from damaging a stylus, etc. It will require a P-mount cartridge, but very good ones are available -- I'm fond of Stantons, but there are plenty of other choices as well.
I'd expect an SL-7 would need an overhaul by now, something to consider. I'd not get one "in the wild" for that reason, one purchased from someone able to get it back into new condition would be advisable.