Checking dimensions for the real thing, Evergreen 263 - .100 channel will be only slightly undersized so should look reasonable as a replacement bumper. Using a stock size means I can be consistent on any future builds.
What isn’t immediately obvious from the photos is that I’ve “turned” the ends of the front axle in anticipation of the wheels, I much prefer to avoid the straight ahead position unless I have no choice, I think it adds a little “life” to a model. Nothing more sophisticated than tweaking the stub ends with fine pliers, then reinforcing the opened edge with a sliver of plastic welded into place with solvent - once properly set it should be strong enough.