interested to see cause running into many people including y self waitng 3 hours or 4 matchs of denial of our primary (mid) when wee get it someone leaves lobby and than we are back to waited for our mid to pop up which is like 2/10 matchs.So seeing if we can bring some mid lan champs to top .
Well, separate the lane from the role and you know what to do.
If you absolutely must play Vel'Koz, consider what your team needs. Think you can play him decently as a tank? Build him tank. Want to deal damage, but be able to take a bit of punishment? Build bruiser (ROA, Sceptor, etc). Have a tank jungler and an AD assassin? Build him mage.
Just because he goes top doesn't mean you have to build differently, but you need to form a cohesive team composition and consider your build appropriately even if you were in the mid lane.
Although, I guess you could throw in a Nashor's if you want tower pressure and pushing power. Sustain is one consideration you may need to consider, especially mana.
When I do it, I see who am I matched up against. If its close ranged melee, I usally go rylais
or icon 
first ( depending if I'm winning or not )
If its a ranged champion, you can be safer with a roa. 
or if your snowballing and want to be greedy , start stacking a tear
( the mana will help you hrass safer ).
essentially the only thing that changes in toplane other than mid, is the first 2-3 items. You want to build tanky straight away, without sacrificing too much dps, After that proceed to build your regular build.
Edit:
Just so I mention this for other people. the benefits of playing vel koz top is that he is a tank killer. no matter what resist your enemy has, you will always shred them due to your passive.
The negative effects is that he is squishy, and since the lane is longer, you must be really aware ganks. I usally save my E only for when they engage on me ( jungler or laner ) and poke with the W mostly. Only use your Q as a safety net if your enemy gets to close, or when you want to finish the kill.
Velkoz top is pretty viable, but it really depends on skill. Unlike other match up toplane, no matter who your up against with velkoz, if you misplay your hand, you will loose ... But if your a good velkoz player, 90% of your melee matches go in your favor, and you can burst the other 10% that are ranged
So final build would llook like
or
If you're just looking to bring mid lane champions to top, and you're looking to have a frontline, you can pick people like Cho'Gath, Elise, Gragas, Kassadin (decent off-tank if the enemy team has lots of magic damage), Lissandra, Ryze, Swain, Vlad, etc.
Now, if you want to just counterpick enemy top (or laneswap), you can pick someone with long-range poke, preferably with some CC or mobility so you can survive the engages. Vel'Koz is one. In this case, you probably want to build like a mage and not like a tank, unless you plan to do an off-meta tank Vel'Koz. I'd imagine that build would focus on a bunch of tank CDR items, relying on passive to do most of the damage. If you're not doing a tank build (do this only if you have decent frontline elsewhere on your team; one tanky support is not good enough), just build like a mage with focus on poke items (Luden's, Liandry's, etc.) so you can harass more effectively.
I have game plays of velkoz top and in ALL others roles and lanes too. Check it out in my playlists: Johnny Sythe
