Don, here's some good news...if you have a 5.14, the swap to a 4.56 pumpkin is exactly the same procedure as the swap to a 4.10 pumpkin...and the 4.56 pumpkins are realtively easy to find compared to the 4.10's. Switching to a 4.56 would give you an 11.3% increase in top end over the 5.14. Switching from a 5.14 to a 4.10 would give you a 20.2% increase. That's a pretty big jump. Since you are running a 216, you might want to give a 4.56 a try before jumping all the way to a 4.10.
I could point you toward several 4.56's here in Arizona if you want, but finding one closer to your home would be a better bet because the pumpkins are heavy (over 100 pounds) and shipping isn't cheap. If you find a local one and can buy it right, it might be worth trying. If the gearing is still too low, you can always continue to look for a 4.10.
You probably know this already, but another way to increase the top end is to go with larger diameter tires. I wanted about a 20% increase on my '57 3600 that had 4.56 gears and 17.5" rims. I ended up with about 21% by doing the 4.10 pumpkin swap and changing over to 19.5" rims with 8R19.5 tires. After I did the conversion, I discovered that my clutch was too tired and slipped during take off, so I had to use the granny 1st until I put in a new clutch. Everything worked OK with the original 235, but it strained it a bit. Since then, I installed a 261 and it is a very nicely matched set up. I share this only because these old trucks sometimes respond better to changes in small increments instead of large ones. Components can get strained that we don't think about as we dream up improvements. For example, I had no idea that my existing clutch wouldn't be able to handle the pumpkin/tire conversion. The ankle bone is connected to the knee bone, the knee bone is connected to the hip bone, etc.
Incidentally, I forgot one expense item in an earlier post that you will have regardless if you swap the pumpkin or change the rear end. Add in about $100 for either one to get a speedo adapter.
Matt
PS--The rock crawler crowd is always on the prowl for the 5.14 gears. They are valuable, so you should be able to sell them to recover a good chunk of your conversion cost.
