Auxiliary fuse box power wire

[Dino]

I bought one of these fuse boxes to provide power to all this aftermarket stuff I'm adding.  

http://www.ebay.com/itm/351246895861?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I may bolt it to the top radiator support. I'll need to run about 2' of wire to the positive battery terminal and the wires from the box would run along the inner fender and through the clutch cylinder grommet inside the cab. If I choose this path then what gauge should this main power wire be and what size fuse do I mount between the battery and fuse box? I could mount the box next to the fender tag but I'd rather not drill any holes there.

Alternatively if I can find a spot for this box on the firewall, and that may be a big if, then I could tap power straight from the starter relay. The wires going into the cab would be shorter but I already have 2 6 gauge wires and an 8 gauge wire bolted to the starter relay. Would adding one more be asking for trouble?
I could possibly mount the fuse box somewhere under the dash and run only the power cable through the grommet and to the relay. That may be the cleanest solution.

Is one location better than another?

[PlainfieldCharger]

Hey Dino,

I found this article from Crutchfield for Wire size needed for amp draw.

http://www.crutchfield.com/S-XHd18n9Kjr8/learn/learningcenter/car/cable_gauge_chart.html

[Dino]

Thanks buddy! Bookmarked that one. 

Looks like I'm going with 8 gauge and a 50 amp fuse.