Todd -- Welcome!
Read This before you get too crazy thinking about transmission upgrades.
Food for thought -- rebuilding your 216 is going to be expensive, even *if* you can find someone near you knowledgeable enough to deal with the poured babbit rod bearings that engine has. Original is neat but won't get you modern cruising speeds.
One thing to consider before swapping engines ... is your truck titled off the engine number or the truck's chassis number (VIN) on the data plate on the driver door pillar? If the truck VIN, then you are good to swap. If the truck is titled off the engine number, you can still swap engines, but you will need to deal with paperwork down the road. And you will have to keep that 216 on hand until you do.
If you swap engines, the 235 is a good choice, and certain ones won't need much modification. The 261 is also a good choice (it's what I went with in my 3804). The gang in the engine forum can answer more questions about that swap.
Swapping out transmissions is a much harder project. But the boys in the driveline forum can help you there.
And lastly, if you are going to be upping your cruising speeds, please make sure your brakes and steering are good to go, as well.
Glad to have you!
John
