Well, being that many of those Kusan items were later reissued by K-Line with plastic (and also die cast K-Line trucks), you could certainly use those.
BUT I use a truss screw along with a stop or lock nut (the type with a nylon center). On a car like a flat or a gondola, I either paint the screw the car color or use a pre-blackened hex or button top screw. I tighten it all the way, and then loosen it just enough to get friction free left to right movement of the truck.
The key to derailments is not weight, but the manner in which the trucks are attached to the car body. As manufactured plastic truck sets are attached using some sort of rivet and most of these have wobble of the trucks. Grab the coupler and try to move it up and down: If you get a lot of movement, you will have derailments when pushing a long train backwards, especially through tight curves, switches and "S" track configurations. Even rolling stock with die cast trucks attached with a screw still have an amazing amount of up/down wobble.
I reattach my truck sets using the screw/lock nut method and pushing a 20 car train backwards through 027 curves, switches and "S" configurations - with short 8-inch Lionel 027 cars (with my remounted plastic trucks, no weight added) right behind the engine - and I get zero derailments. Even with the short cars with plastic trucks pushing much heavier cars with die cast trucks... still NO derailments.
The only rolling stock I ever add weight to are ones with plastic trucks and single roller pickups for illumination, like a caboose. And I add weight to reduce the light flicker of these cars.
There are slight variations between all the manufacturer's truck sets. They use differing types of screws (with the die cast trucks), and in the case of the Industrial Rail die cast trucks, the coupler arm is a longer length that other types. The original K-Line die cast truck sets had screws of different lengths, depending on the sort of rolling stock they were used on. In the case of the later produced K-Line trucks used for the Train-19 rolling stock (and later for the original runs of RMT rolling stock), the height of the mounting area of the truck sets are lower: For rolling stock with thicker bodies around the truck mount area (as with the K-Line traditional caboose - also the Kusan one), this is good as the car will not ride as high on the truck sets.
Another example of this would be to take a look at the K-Line traditional off-set 2-bay covered hopper which was also originally a Kusan item. There's a mounting nub on the plastic frame of the car, which served the Kusan truck fine. The K-Line die cast trucks ride high on this car as no alteration was made to the frame. Many complained at the time about the "high-water" appearance of those cars, never mind the excessive wobble of the trucks. I take those very cars apart and grind down the mounting thickness on the frame of the car with a Dremel, so that it rides lower to the track.
So what I'm saying is that you may have to be prepared to make some small alterations to the car bodies depending on what types of truck sets you use. And you'll have to be creative with the types of screws you use, if you use die-cast truck sets... the screws included with the sold separately Lionel die-cast truck sets may not be long enough for all applications.