Need help with fixing a map for SFM

Ok, so I’ve been working on a project for a few weeks now. Decompiling and fixing a map for SFM.
I have worked very hard, since it came packed with custom textures and models, so I had to extract them all individually with Pakrat, and then fix broken textures in hammer.
I have very little experience with any of these tools before, so its been a real chore, but I’m happy with the final-ish product.

I had started a thread before on how to go about doing this, and all was working well until it came to rendering.
The map looks done, but it was horribly unoptimised, and the process stuck around 4% in the portalflow.

So I went about optimising it, removing brushes I didnt think were necessary for SFM, and cutting down on the skybox, and it seems I made a leak somewhere, or caused an error like one. I dont know.
All I know now is I have two VMF files, and neither of them work.

I’m stumped and demorilised, and I’m hoping one of you guys could look at the problem for me.
Any ideas?

Link to my work so far:
http://www.gamefront.com/files/24226603/NecroSFM.rar
(Includes the custom textures and models, and the two VMF files.)

Link to the original map:

P.S I know that decompiling a map is looked down upon, but its a wonderful map, and I think it has potential for SFM.

I use this to decompile, and it seems to work okay, and it also has an option to automatically extract custom assets:

http://ata4.info/bspsrc/downloads.html

I have already decompiled the map using bspsource. The problem is I don’t know what I’m doing optimizing/fixing errors and leaks in the map I have.