Thank you for some real constructive criticism. Your right, Yorick is a good champ and i want to cover up his weaknesses. Im pretty sure i have frozen heart and spirit visage in my build. The CDR and Mspd runes may help too but i like having early res's and health. It really works great either way.

I really like your build and am happy that not all people are so narrow minded when looking through builds

I like what you doing working to overcome his weaknesses, but i feel like you could compliment him a lot better with some different items. Adding some movement quints really helps make yorick a good chaser, when you combine it with CDR mysteries and items like Spirit visage & Frozen heart which will let you keep his q up 100% of the time making him impossible to out run.
So i dont think your build is bad, but i think you could get some different tweaks that would work better as a whole.
if you want to look at some different ideas here is mine just to show you what i mean.

http://www.mobafire.com/league-of-legends/build/yorick-annnd-shovel-to-the-face-196270

Warmogs is a waste of money since it is expensive takes time to build and doesnt give much more than flat health. I like getting frozen mallet instead

Should rush warmog's first.

Frozen mallet is a strong item for yorick b/c yorick absolutely sucks at chasing even with his slow ghoul. The stats it gives comes from the items that are in its recipe. You don't want to be stuck with a phage and a giants belt in ur inventory hoping to get a slow.

Maw is a strong item since without damage items yorick will fall off so hard he wont even be noticed in a team fight. Instead of getting a bloodthirster getting maw also doubles as an m res item.

R u kidding? GA is the best late game item hands down. The revive it gives is so strong if they focus you. You never want to waste ur ult on urself or else your carry wont have a revive or another clone of himself.

I really dont think that you need any more mana besides manamune b/c unlike ryze his spells don't scale off of mana. As for the Trinity force, It is so expensive by the time you get it you will be melted before you have a chance to get in close to proc the sheen.

and btw i bet u didnt read the optional items b/c i said you could choose what items to get and i listed plenty for u to choose from

3 of your core items on this build are not so great for Yorick.

First off FM.

The pattern for that item is 800g and gives 45hp and 2AD. Pathetic stats. Rushing this item is really gimping yourself. On top of that Yorick doesn't have any synergy with on hit effects and you are leveling q last meaning that you wouldn't want to be in a fighter's melee range anyway to use this most likely.

Second, the Maw

Maw is a conditional item. It's over costed and under stat'd. It's a gimmick and a counter build item... not a core one. The reason you think Yorick falls off late game is that you build him non-effectively. He's great late game if you build him well.

Third, the GA

Not an item for Yorick. His ult already does this for someone...if they focus you, ult urself and be happy that they are ignoring your carries. The GA is for people not wanting to be focused, not the guy with inherent life steal and 20% damage reduction just from skills.

Look at the top Ryze builds. This is similar to how Yorick should be built- gaining offensive AD from mana on defensive tank items. Throw in a Trinity Force along with these tanky items and Yorick stays mean all game long.