depending on which
LR variant you are planning on using, you could upgrade one. and possibly top one tank off with a pintle
HS
I enjoy your inclusion of
GK 
even though they're expensive as hell. I too am trying something similar (but with GKMs, not GKTs)
and I dunno what a 'poison'hound does, and I'm not all to familiar with what a Vendetta has, but I'm pretty sure you might wanna go with a Vend. you could possibly use it as a trans vehicle for one of the vet squads, and drop them right where you need 'em
personally though, I don't think you have enough templates. but I forget what the GKTs hold, but I know the psycannon is only heavy/assault 3. I mean, yes you do have flamers, and I don't know which
LR variant you're using, but I would go with either a Demolisher, Punisher(if you want another big gun), or a plasma tank.
if you're wanting a standard
LRBT, change the hull/spons combo to lascannons(or plasma cannons). it will be targeted alot, but you can put it behind the termies and try your best to have them give it cover while they move. with a LRD or LRP, your hull/spons combo is perfect, but with a plasma tank, you will of course want plasmacannon h/s (and likewise, this tank will be a priority target for the enemy) but on the plus side, you have a chimera. and don't forget about Pask for your tanks. I think he's like 50pts(?) for BS4 on one tank, and I THINK you can re-roll for hits with that tank or something...
I'm assuming your Griffs are one squadron, but you could replace one with a Meduse w/ BB shells.
(a downside, with 89 points of breathing room, you wont be able to take more than one of these courses of action)
and I haven't read on GKTs, do they get Shrouding too?
but for a tank that you want to deploy as far back as possibly, I'd atleast go with a