A couple of things caught my eye in your post. First you said you are a 27" draw length, but would be shooting a 28.5" arrow. This seems very long to me. I shoot a 27" arrow with a 28" draw length. There is really no need for the extra length on those arrows. You are correct about the average weight per inch on arrows, but as BGfisher said don't forget about components.

Check out the arrow weight estimator on bowjackson.com and that can help you figure out what your weight should be around. As far as figuring out the KE, the best way to do that is to chrono your bow with your arrows once you get them and know their weight and use a KE calculator on the web.

Personally, I like to keep my arrows at around 400 grains. I feel that this gives me a flat enough trajectory for hunting while maintaining a decent weight to aid in penetration. Some have had great success zipping 300 grain arrows through deer while others are lobbing 550 grain arrows through deer.

Also, before you worry too much about KE check out this link:

http://www.bowsite.com/bowsite/featu...tion/index.cfm