Hextech Gunblade is not a very viable option in my opinion. The guide itself also needs some work as it is hard to read. I will change my vote when I see needed imporovement.

I like the build.

I think you've done an okay job, just learn to code the guide to make it look better. Refer to this guide for details.

I question the Hextech Gunblade as part of the build only because his AP ratios arent that great and most of your damage as Kog'Maw should be from basic attacks (assuming it's AD not AP kog) Still, solid guide though.

Good guide, just lacks some coding and its decent. Personal preferance though: I would never pick bloodrazor as kog maw, ever. The reason is because he already has the "unique" effect, and unless the enemy team is 100% bruisers, i find it unescessary, because it becomes an overkill item. Guardian angel should be listed as a potential to swap it out with if the team has few or no tanks.