Sounds like a great project! Did you stop by the site before or during your resto??
Even if you're only finding us now, we glad you got here as quick as you could!
I truly hope you didn't put too much $$ into your 216 ... Because, if you upgrade the rear axle to the 4.10, you are not going to be happy with it after a while. At least that's what I found driving my 3804 -- it could hold 60-65 okay on level terrain, but it got winded pretty quick on hills and in heavy traffic/traffic lights/stop and go. And forget about passing anyone. And you will still need 1st gear just to start off. IF you find the 3.90, I think you will find the gearing too tall for the 216 -- especially if you are running 17-inch wheels (I am).
On my '49 1-ton (3804), I'm running the 4.10 gearing behind the SM-420 and a '54 casting 261 engine on 17-inch wheels. It can cruise 70 mph all day long and is still good in traffic. I generally keep it to 60-65 and it is very happy there.
The SM-420 isn't optimal at this point but it does fine AND like all the other components in my driveline, is completely bolt in with no mods required. I even used to kit from Jim Carter (other vendors sell them too) to disguise my 261 so it looks like a 216... well, except for the Detroit Diesel "Alpine Green" color ...
The only thing about the disguise is that the 235/261 valve cover was a vast improvement over the 216 VC ... which LEAKS...
But you are on the right path to do something about your steering before you go faster. Hopefully, you did your brakes, too.
Again, welcome. We hope you find a home here among your brother nut jobs ... Um, I mean antique truck enthusiasts