its not the heads fault that it looks out of proportion...
Simple you may have scaled the model correctly, but the perspective on the limbs - in particular the shoulder and waist area's make it look out of sorts.
take a look at the shoulders, you've placed them higher which is great for a guy with Wrestler or Body Building muscle tone, however you've given him just more of an adverage guys muscles (which arn't greatly defined at that)
the diaphram area is also wrong for the design of the model, as it is very wide but not greatly shaped ... i know you're trying to keep this model low polygon, but to keep a model low polygon its just silly to focus all of your polygons in certain area's and then skimp on others. The idea of low polygon modeling is to share the count throughout the entire mesh.
the shape of the legs is also very odd, as what you've done is tried tp shape the muscles evenly and if you look at the legs of someone with more muscle they're very close together because of the muscle bulge which is affected by gravity so slides towards the middle. So you need to show this offset in the models shape.
also to keep you're own weight you can't stand like a normal guy, you've got to widen the legs so they wouldn't bend inward in such a way.
http://www.wwe.com
would be a very good link if you want to shape him as a muscle bound freak and keep him looking right... also i'd suggest when showing off muscle guys not to do so from a front on veiw a they always look weird, especially untextured.
and important thing to remember is to make sure you're ONLY mirroring the Left<->Right along the centre of the model, and more mirroring limbs themselves, as you have to show the muscle tones with gravity affecting them as well as the subtle shapes caused by the extra more defined groups from the build up.
if you want the head to look more in perspective, make the diaphram area slightly thiner - do a slice about halfway between it and the waiste then move its vertex up using softselection so it curves at the diapram and use that to shape the bicep area.
also pull down the armpits to add some top bulk to the muscles, as it will define that area much better.
i have a feeling you're not going to listen to me and probably flame, but its worth a try to help you atleast once
Tsu'va Oni Ni Jyuuko Fiori Sei Tau!
One block follows the suit ... the whole suit of blocks is the path ... what have you found?
