To sell (and get another) or NOT to sell, your thoughts?

[BIG CTY]

I bought my rusty but trusty bucket back in September. She's a 25 footer at best. Straight 6, converted three on the floor, and all kinds of rust. The truck runs like a d@mn top, it's seems like you just cant break it! My truck has loads of character, but not loads of power. The straight 6 has some balls, I can still burn the tires up at the drop of a dime...er, uh...clutch, but I want more power. I thought about putting a 350 in the good ole bucket, but yesterday I noticed yet another chunk of my truck laying in the driveway. I'm sure the truck isnt beyond repair, but as much as I love it in just these few months, I'm thinking maybe I should find what I want and give up my bucket to someone who'll be able to bring her back. Here are several pictures of my bucket. Several of the pictures are VERY flattering, I sent them to the insurance company.

I have been offered $1800 for my bucket. I found a 65 stepside C10 with a 350, 4 speed (which I've wanted), and in significantly better shape than mine. There is a small about of manageable rust. I've been TOLD that it runs great, but I KNOW mine does. The truck should be about 3 grand. So tell me, what would you do?