I have eaten surplus cocks of a few breeds over the years but to be honest, there's rarely that much meat on them. Marans and sussex are meant to be good dual purpose breeds, but I've found them to have big, tough leg meat and no breast at just a few months old 5 or 6months. But my adult birds are fed mostly whole grains and are totally free range. Not worth my while plucking and dressing them to be honest. I think next time I'd skin and gut and just make soup/stock.
I would suggest in the first instance choosing a meat breed - (tired after no sleep and a long day!) think ixworth? and there's that french one I can never remember anyway and rear them to the book, give them all the right food, keep in a pen and kill when you're meant to. Because i have found extensively reared dual birds not that good. I'm sure others will post with much more and better experiences than me!