What is the approximate maximum speed of the Chevrolet C50 Truck 220 hp of the year 1968 ?

hi.
155 horsepower 1968 250 CID I6 Engine
This engine was capable of producing 155 horsepower at 4,200 rpm and a torque of 235 pound-feet at 1,600 rpm. It came standard with a three-speed manual transmission, while Powerglide and the Hydra-matic transmissions were available as optional upgrades.
or try this link.
Chevrolet Wikipedia
https://www.classicmuscle.com/resources/chevy-ck-trucks-history

https://www.quora.com/What-is-the-displacement-of-the-engine-of-a-1962-Chevrolet-C80-truck
Here is a site that you will have to open for the information.

all cars can hit 85 to 110 mph.

Gasoline Engines

The 1969 C50 pickup truck was available with three different gasoline engines, including a 292 in-line six-cylinder engine that produced 170 horsepower at 4,000 rpm and 275 foot-pounds of torque at 2,400 rpm. Other engine options included the 350 V-8, which output 200 horsepower at 4,000 rpm and 325 foot-pounds of torque at 2,000 rpm, and the 366 V-8, which generated 235 horsepower at 4,000 rpm and 345 foot-pounds of torque at 2,600 rpm.

Diesel Engines

Customers that were interested in a diesel-fueled 1969 C50 had a choice between the Detroit Diesel (4-53N) engine, which offered 130 horsepower at 2,800 rpm and 278 foot-pounds of torque at 2,000 rpm, or the more powerful Toro-Flow Diesel (DH478) engine, which output 165 horsepower at 2,800 rpm and 337 foot-pounds of torque at 2,000 rpm.

https://itstillruns.com/specifications-1969-chevrolet-c50-truck-7808813.html

https://www.quora.com/Which-is-the-approximate-maximum-speed-of-the-Ford-truck-F600-V8-of-the-year-1965

Hi Diego.
this link should help you out.
Chevrolet Wikipedia

The maximum speed of the truck Mercedes Benz 1112 diesel 6cyl 120HP 1968 was about 85 miles per hour. This was one of the lightestof the diesel buses.
The maximum speed of the truck Mercedes Benz 6600 diesel 6cyl 145HP 1956 model was about 85 miles per hour. The bus delivered about200 horsepower when turbo charged.