How old is this, I don't know when Gunblade came out, but starks was never really good on kaiser, granted it's still a godly aura, and should find it's way on every team, Morde never had any physical damage, and the armor reduction didn't even apply to Mace as it's been magic damage as long as I can remember... but this is so old I don't know if Gunblade was out yet.
The original gunblade was gods word to Mordekaiser, blows bloodthirster out the water on Morde, it's a little close now but the slow bullet is indispensable still. Ima just assume this was before some of those items, but back than Haunting Guise had spell vamp so it was a good choice, and spirit visage has been secretly good for ages with improved health recovery for his ult, any health regen items and spell vamp and lifesteal which may apply.
Let's just say those items weren't out at the time. Currently Morde works best with Dorans Shield, boots to Mercury Treads, Bilgewater Cutlass to Hextech Gunblade, Wardens Mail to Randuin Omen, and Abyssal Sceptre.
Frozen Mallet doesn't help him reach his opponent like Gunblade bullet, and Rylas usually procs 15% on Mordes spells... Without movement boosts that's just not enough. With 50% slow from gunblade, wile also giving his Q high spike damage and lifesteal, ap and spell vamp, it is a cure all for Mordekaiser. Randuins Omen fills in his health, health regen, and armor, wile offering cooldown for more offense and a second slow in an AoE. The 2 activate slows offer enough to catch an opponent as often as you have an ult, the rest of the time you should be teaming up to gank anyway.
Oops, work is over, n forgive my phones auto correct if I have a few weird words on there. TTYL
Edit: OK back. So anyway, with this build you have the best variety of spike, slow, armor and resist, some cc reduction and cooldown, and all within 4 items.
Will of the Ancients should be on an AP carry so you can double benefit. Rylas will take to long to make and offers less item compression than getting Hextech Gunblade to cover spell vamp and slow. And trying to get Bilgewater Cutlass early rather than Hextech Revolver will offer you better spikes with 1,2 attack proc using Mace of Spades, and a slow so they don't walk away wile you throw the kitchen sink at them for a successful ult. Simply sustaining is no comparison to sealing a kill and eliminating their offense wile improving yours.
But depending on how your income is you may take Hextech Revolver first and even take Rejuve Bead to get a little more regen and build up to Warden Mail.
Late game you'll adjust appropriately to the battles needs, if the opponent AD carry gets out of hand you can build Thornmail and exchange Randuins Omen for Warmogs... If the AP gets out of hand the Mercury Treads and Abyssal Sceptre should serve fine and you can just graduate to more damage like Rabadons Deathcap or Lichbane.
If you use Lichbane try to get Procs on your Mace of Spades so it will do magic damage instead of physical, which will benifit from spell vamp because it adds onto Mace of Spades...
Beyond that you can just try out stuff and try to be flexible. Mordekaiser seeks an early game lead and you shouldn't let the battle extend much further than the first 4 items, Mercury, Gunblade, Randuin and Abyssal. If you play defensive and bait you should find opportunities to catch a ghost, than use it to push down lanes if you survive, send it in front and throw Creeping Death on it to tank towers.
Just be mindful of Mordekaisers limits though, the old 1 vs 2 days are gone, if you get ahead is something that applies to any champion, but in the first few levels before you flesh out with items you can get harried easily with just a little crowd control, focus fire and quick opponents.
Oh yeah, and Mordekaisers jungle isn't very accessible til lvl 4, skills 1/1/2