Its amazing what you can do with a bit of greenstuff & glue.
Ive done two repair jobs like this - the first was when I first started, so its a little primative.
http://www.dakkadakka.com/gallery/31244-Resurrected%20Rhino.html?m=2 The second was a predator, which I started for the Nitty Gritty Comp but didnt get finished in time :(
http://www.dakkadakka.com/gallery/images-14062-5008_Darkkt%27s%20Steel%20Decay%20Legion.html I found a few things that helped with the predator:
* Blobs of greenstuff on the bits I wanted to hide, which I then 'stabbed and pulled at' with a pin to get texture.
* tiny blobs of glue (regular glue not plastic or super). This (done carefully) creates a bubbling effect, thats quite subtle, but highlights well.
* Weathering/mud - great way of hiding a load of sins/ugly bits. My mud was green flock sloppily glued onto the tracks, then highlighted up.
It'll be good to see the spin you put on this one! Its looking good so far, my only comment is to not add any more spikes, and to greenstuff/blend in those Tyranid infestation markets.
Cheers mate