If you want the 6A with the tyrant why give him the longsword? If the plan is to use the longsword only against enemy characters that have WS6 then its not really worth taking- instead think about taking a great weapon: you dont need to use it but it'll be helpful if you come accross big enemy monsters, heavy cav or heavily armoured enemies.
As for his set up I feel its a little weak in general- I think that greedy fist/gut maw/greatskulls are musts on generals. The spangleshard is pretty awful, and if you do the maths (I did it myself but there is a copy of it at 'The Ogre Stronghold') you'll find that the wyrdstone is just plain better. Wyrdstone, greedy fist and luck gnoblar is the basic defensive build that I start with on my tyrant (though the greatskull is nice too).
With the BSB, since he has no magical banner you can give him magical equipment (just not a mundane weapon.. shame or an ironfist, gutplate and HA would be a nice combo). I would be tempted by the armour of silvered steel for a 2+ save (helps keep the vital BSB alive) or the gut maw so that if you arent facing any nasty enemy characters you can challenge and get a few wounds back (or an extra wound).
The butcher is a good set up for 7th ed but illegal in 8th. The dispel scroll is now just a basic arcane item and so you can't take other arcane items with it (and no multiples). Having said that the bangstick has lost its best features- its now just an extra magic missile... but needs PD to cast it. Personally I doubt I'll take it at all in 8th.
The arcane item that I love to take is the skullmantle, which is utterly awesome, but whether to take that or a skullmantle is an iffy one. Does free up some points which can either go on other characters or on getting the broodcleaver or siegebreaker. The first tries to get some of those lost wounds back while the second means the bucher can take on enemy heros (as long as he can surcvive a few rounds- I always miss my attacks).
Bulls- I think that AHW is now pretty rubbish for bulls. I would just keep them with ogre clubs if you are going to use ranks... and I would increse their numbers. In the few games of 8th Ive played with my ogres so far units of 4-5 bulls just didnt do very much: big enemy block units hit before you, are stubborn and you just dont have the survivability to take that for mulitple rounds. I've been using units of 9, and Im not sure if I wont up that to 10-11 (just so I can get hit and still have 2 ranks- certainly helped by characters).
Ironguts- Im not too sure about them- with the nerfing of cavalry and the emergance of lots of large blocks of infantry I think bulls with bruisers (or near the general) may well be a better option (and they are 3/4 the cost, so you get more wounds and more ranks). This all needs a lot of playtesting... but I would keep it in mind when you play with this list.
Leadbelchers- I simply cannot say how much I hate these things... but thats because they hate me and always misfire. If they work for you keep them, but I think that the points would be better spent on a big unit of gnoblar and a scraplauncher- gnoblar are so cheap that they are just necessary (Im using a hoard of them to go up a flank- terrifies the opponent and only costs 60-80pts) and scraplaunchers are just beautiful in the new rules.
As for the new %s composition you shouldnt really worry too much with ogres- you'll never break special and rare can only really be broken with units of maneaters. I've pushed the lord limit by squeesing a tyrant and slaughtermaster into 2k but heroes arent really an issue anymore... and if you havent hit 25% on core then something has gone very seriously wrong