I have a recipe for a 5 gallon batch of porter:
1 can of Dark Malt Extract
2 # of Dark DME
6 oz of Chocolate Malt Grain for Steeping
8 oz Malto-Dextrin

I was able to get most of the ingredients in correct quantities except for the Chocolate malt I had to buy a pound of it. Considering i have more than double the amount needed in the recipe, how much more of the chocolate malt could i add to the batch before it would adversely affect the end product.

If you're trying to follow a certain recipe, than I'd say stick with it and don't try changing the amount of chocolate malt. Chocolate malt is a pretty dark malt with lots of character. If you overdo it a little, it probably will taste like you overdid it a lot. Stick with the amounts the recipe gave you, and you'll have enough chocolate malt for next batch, if you like it. Then, if you want to add a couple extra ounces, you'll know what kind of effect it'll have on the beer.

Thanks for the Advise