Todd, Welcome Aboard. And ditto all the above. I too have a 3600 with it's original 216. And I too wanted to honor the original drivetrain of the truck. It's a low mileage '51 that worked on a farm and lived in the barn till it had a amateur restoration and wound up in a small museum. And then it had the misfortune (or good luck) to land at my place.
45 MPH was the little truck's happy spot. Then a set of 4.10 gears replaced the stock 4.57s. 55 MPH became the new good speed. Then the need for "more speed" popped up and a T5 transmission with a .72 overdrive 5th gear replaced the stock, stump pulling SM420 transmission. Now, on flat ground with no headwind, 60-65 MPH is a good cruising speed. While getting caught up in big city traffic when traveling, it's seen 70-75 MPH.
However if a small hill or a 10 plus mph headwind hits, the speeds come down quick and it's time to shift to 4th and run 50-55 mph.
I do have a 1959 manufactured 261 engine, cast in the 1954 block mold (making it a true drop in upgrade) waiting in the wings. This is a desirable change since to all but the extremely knowledgeable it looks like the stock 216, but has almost double the HP.
The point to the above ramble is that in flat country a 216 can work in today's world. But if in hills or mountains, a bigger engine is a much better deal. As you do your DD, you'll see that you can upgrade and keep the proper look when you raise the hood.
Good Luck,
RonR
Last edited by moparguy; 04/22/2020 1:31 PM.
