a few notes:
the wyvern is very bad, considering that if you really need anti-infantry stuff you can have 3 heavy weapons teams with mortars for 99 points... That's 9d6 hits instead of
4D6, I'd say that's clear enough.
Also, I understand the "completely mechanized" thing, but I'm not sure having so many Chimeras is actually useful. With those points you could have like 2 more Manticores (which are awesome), or many other things.
Finally, but most importantly: where are Pask and the tank commanders?? They are simply the best units in the codex

do whatever you can to sqeeze in one or more of them, they are just powerful.
In case you are interested, here's how I would make a 1500 pts army

that's very different from yours, but you could still make use of some ideas, who knows. It's a brigade and lots of guys are on foot, which
btw is something you will need, because ur opponents tend to rush towards ur troops, AIP near you and charge, etc, so you need layers of expendable troops to use as screens for your big guns.