Green for go ?!?

Whoop-whoop. Last night was my longest run since late Feb. A whole 8 miles!  
Don't laugh... My running and general fitness is dire at the moment but with the universe's biggest half marathon in 39 days!!! I really have to get a run or two in. 8 miles near enough, is roughly, kind of close-ish to 3/4 of the the 13.1 miles.
Divn't get me wrong, last night was by no means quick with it taking me 1hr 25min but it felt good to run non stop. My legs were getting a bit weary with a mile to go but overall I was fairly pleased. The route was 7, figure of eight laps around Scunthorpe park which included passing the ice cream kiosk at least a dozen times which was friggin torture for a fat lad. 

My ickle dilemma is do I wear my bright green Saucony Fastwitch trainers for the GNR or my cushioned Brooks Adrenalines. Since I stopped wearing my Brooks my achilles hasn't bugged me at all but with the Fastwich being a heck of a lot thinner on the cushioning, will they be ok for an overweight 6' 2" running machine over 13.1 miles?   I'm 75% sure it'll be green for go but we'll see. I'm going to try and get out for 10 miles next week with the green speed machines strapped to my feet.