Not a big deal but probably not worth it to take a shield on the BO warboss since hes got armour (save) that can't be upgraded any further and talisman (ward) that is better than the parry ward from 1h + shield.
I like chukkas but why not drop all 5 and take 1 more lobba and 1 more diver as you have the points allowance under rare cap and would free up 10 points as well. I just find divers and lobbas very effective (well as effective as you'd expect for an O&G unit hehe) and fun to field.
You could also drop the chukkas and bump the river trolls up to 12 strong and make them an absolute rock with 12 vomits and so many wounds. The models are just awesome too.
Don't have any manglers yet myself so can't comment, but the new resin model just looks all sorts of crazy bouncy killiness
Boss on wyvern is hella fun but i'd rather take another unit block of something else. If you want him in there to go after seige and be a fire magnet then perhaps bump him up to a BOWB with HA, Shield, Dragonhelm, Talisman of Endurance (2+/5++/2++ vs fire).
For your BOWB general, i've always had best luck and fun kitting him out with HA, Enchanted Shield, Talisman of Preservation, Basha's Axe. Tough as nails and mean as frack.
BOBB BSB should have armour of destiny and shield so you can utilize the only other 4+ ward save available to O&G and he gets and 4+ armour save as well. Remember you can still use his GW at the start of combat phase with that rule about "I'ma usen 'dis one", just remember that his AS goes to 5+ when you do and you can switch back on your next turn.
For both of your lvl shamans, perhaps sneak some MR items on them since combat characters hog all the ward saves hehe. I like to put my lvl 4 GOS with my BBWB so they protect each other.
Up the Orc Shaman to a Lvl 4 Savage Orc Shaman and take that lucky shrunken head thing for warpaint bonus and put him with the general. And then toss the dispel scroll on the night gobbo shaman.
Perhaps take a pair of lvl 2 night gobbo shamans and give one the dispel scroll and the other a scepter of stability.
The savage orc bb on warboar is kinda nakid but, well thats the point.
I find too big of blocks to be unwieldy so maybe go with a pair of 60 strong night gobbo archers allowing you to take more fanatics. If you want to go with just one big block then perhaps take a night gobbo bsb instead, with the spider banner and then a night gobbo shaman can buff the blocks poison attacks to 5+ :}
Try perhaps to up the sav boar boyz to 14 strong so you can get 5x3 ranks with the bigboss.
Oh well, just food for thought there and hope it helps maybe hehe. GL...