If you get to loading for it,you might contact Mount Baldy Bullets.He has a pretty good idea of just what alloy your 86 will like.
The caution is those barrels were real soft steel and too hard of a bullet can hurt them.
I beleive Mike Venturino wrote a book on "Shooting Old Lever Action Rifles" or similar.Midway may have it.I suggest you order a copy and read it.
Of course,as your Dad's fine old rifle,it is priceless already,but if you have access to a Gun Trader's Guide,you might try to learn just what you have..perhaps for insurance reasons.Like,it might be a Lightweight,octagon barrel,color case hardened takedown and you might be looking at more than $10,000
I am not the guy to teach you,but there is some to learn before you shoot it.
Good for you!!