You sound like you have invested a lot of money into the car. 700 dollar new low milage motor ( if it came down to that ) And a litle more money will get you a long way. Who cares if you can't beat you're brother. I can't beat a top fuel dragster but that does not mean i am going to sell my car. Don't get discouraged. Put that thinking into something productive.
I can relate to what you are saying. My brother has a built (331 carbed) 90 hatch back mustang. It won't be long before i'm a good second ahead but it's something i've worked for and should be rewarded to me anyway. It has been a ''side'' goal for me to beat my brother (but mainly to just be fast in general) So i understand what you are saying.
Lighten up a little and be happy. You can already beat a pretty good amount of other cars out there. Just being stock.
I will be more than happy to help you out in any questions or ideas that you may have.