This will be tough to answer as all my top champs have 2 different rune/mastery pages. 

When it comes to top, you really only have a few things to keep in mind:

- CS like crazy (you should be number one in cs on your team)
- Dont get ganked
- **KNOW WHEN YOU CAN 1v1 YOUR OPPONENT**

With nasus literally all you have to do is stack your Q all game, you should average 100 stacks for every 10 minutes. If you can't manage that in a game you are getting beat. You dont have to fight any1 you dont have to push literally just sit top and get 300-400 stacks then start ganking lanes and 2-3 shot your opponents carries. Nasus can typically take any top laner at or above lvl 6 with 100 stacks, although if they are any good they will just poke/kite you down pretty hard.

With Jax, I don't know his 1v1 mechanics very well as he is a champ I dont top with. But he is strong after level 4, then typically snowballs if he gets any kills.

I would say your best bet for an all encompassing runes/mastery page for top would be:

- Movespeed Quints
- Magic Resist *18 Glyphs
- Flat Armour Seals
- Cooldown reduction Marks

As for masteries, just go defense and maybe 3 points in utility for the extra Movespeed.

Would be better if you use 2 pages so you can have atleast an AD champ/AP champ rune page.

- Movespeed Quints
- Magic Resist *18 Glyphs
- Flat Armour Seals
- AD marks / AP marks

As for masteries go 9 in damage then defense with the 3 points in utility for MS.

I am a big believer in Movement speed as a top laner, it makes dodging a lot easier. You can outrun ganks and save a summoners and you can either kite easier or make it harder for people to kite you. If I am snowballing top I will always get swiftness or mobility boots so I can chase down carrys and wreck late game. As it will typically get more and more challenging to get to carries as the game progresses.