I'm not savvy on 10/22 sights, but have replaced many sights before on many guns. So I'll offer my advice-take with a grain of salt!!
Zero in your gun as is, then go to harbor freight or wherever is around you and pick up a cheap caliper for measuring (got any friends that reload? If they're safe about it, they'll have some you can borrow). Then measure your existing heights and buy accordingly. The 860's are adjustable to windage and height, so that may leave only the question of your front sight-depending on how adjustable the rear is. Gotta remember,most guns only use rear adjustable sights, even the M1A-which I've moneyed around with a fair bit, and the rear adusts up to 600 yds all the same front sight sitting there. So if you buy a matching front sight to your existing, you should be good to go.
That said, there are different heights of front sights, reason is for different guns mostly, but also, let's say you shoot 100 yds more than up close-matches, competitions, hunting in open spaces, etc bUT your stock sights are maxed out, then the lower front sight than your stock, would be a better option, and if you happen across a 25 or 50 yd shot... you have to adjust accordingly, instead of zero at 50 yds, and adjust accordingly to lob in a shot at 100 yds. Thus is why they make different front sights, especially since they seem to market to lever actions-which most of those bullets drop like a rock past 75 or 100 yds. But guys like me hunt with 44 mag, etc, and know we are gonna take longer 100 yd shots, so buy the lower than stock front sight, so the muzzle is higher in the air to lob that 300 grainer where it's supposed to be. In closer shots, like 50 or less, we know we can hit the 8" pie plate or deer/pig, probably without sights, it's the long ranges we're gonna use the sights at their potential. Again, depends on how you shoot, and what at.
Hope this all makes sense and helps. Or, just call Monday morning and talk to the supplier, they probably sell 100's of these for 10/22's, and know exactly what to get depending on how you shoot.