Was looking at how much spell hit would negate a bosses resist ( not counting special resistances or anything) and I got about 162.5 spell hit will do it. This is going off that the boss is 3 levels higher than you (from what I have heard that is how miss/resist/etc. is done) and that about 1 spell hit is .08%. Does this look right at all or did I just completely screw up?

You need 12.6 Spell Hit Rating at Level 70 per 1%. Bosses have a 17% chance to be missed with spells. Now, since spells have a 1% miss cap that we can never get rid of, you need +16% Spell Hit.

12.6 x 16 = 202 Spell Hit Rating (rounded up from 201.6) to completely negate the miss rate.

However, please note, that the number 202 is only if you have NO +spellhit talents in your build (extremelly unlikely). You need to take those into account before figuring out exactly how much Spell Hit Rating you need to cap out on bosses.

I thought they had discontinued the 99% hit cap for spells.

No, they havent. You'll still get occational spellresists against all mobs in game, including lvl1 critters and stuff like that.