Kharnak:
I found the sizes listed,
But had already built a big nasty model. It’s on a 150mm wide by 100mm deep very detailed base. Is it a big deal “not” to have it 100mm wide x 150mm deep?
The “other” way around?!?
Thanks!
Da Crusha:
while it isn’t specified as illegal, Im sure some people might complain that you are modeling for advantage since you will get more flaming body hits. it would be fine with me though. it also decreases his maneuverability.
it makes me think of a cavalry model based sideways. but a bit less extreme.
deadlydeceiver:
But had already built a big nasty model.First off: SHOW US A PICTURE!!! ;P
Kharnak
On your querie:
In your case I'd at last enhance the base to be 150mmx150mm. So you got at last the right flank size... :P
It is true, that the incresed front could become a problem with your opponent thanks to the Blazing Body-Rule.
Normaly a bigger front has mainly disadvanteges for monsters (more models can strike it, decreased maneuverability) while the advantages (being able to bind more unity more easily) are outweighted.
Blazing Body now turns the tide.
So I'd say: In a competetive environment you will have great problems justifying the changed base and IMHO you might even get in some arguments in a friendly gaming group...
So yes, as sad as this is, I'd say it probably is a "big deal" :(
But in the end it all depends on your gaming group.
DD
Bolg:
Just take one corner, measure 100mm from it, make a tiny mark on the base at that point and only ever use the blazing body rule for models toughing that part. (in friendly and competitive play).
Oh and show us pics!
Kharnak:
Okay,
I spun the base sideways, need to add details now to make the front look better. I “previewed” a picture just now, it makes a small “thumbnail” picture on here. Guess I have lots of MB to use?
How does one make a small picture larger?
Example of what I’m seeing…
Abecedar:
Just turn its head to face one side and say it walks sideways like a crab.
Bolg:
Oh, its not even painted just model it on the proper base size, the arachnarock fits so this one should do too.
(looks like an expensive kit bash, very unoriginal but not really my cup of tea)
Zanko:
Looks quite cool imo! :hat off
I would like to see it painted! 
Back to topic - why not protrude (is it the proper word) the legs over the base? Then the body is over the base and evreything is ok!
Btw the wings of a Dragon are also not completly over the base! 
:hashut
Kharnak:
I spun him around,
The front two legs work well for the 100mm wide frontage, I might have to re-position one of the rear ones so it’s touching the base. Only had six used, so four in the air might be a bit much!
Unless he’s going VEDDY FAST!!!