It's a South American truck. I've put a few boosters on those trucks. It can be done but it's a tight fit and you'll need to fabricate an angled mounting bracket for the booster so the brake master clears the carb.
I used an '86 minitruck brake MC on a '65 FJ45 that had '77 axles (front disk, rear drum) and never felt that it needed a booster. I could lock up all the tires without power brakes. I attempted to fit in a booster from a Geo Metro, but that was still too big. No booster would really fit.
Is the truck super hard to stop? If so, consider changing the master cylinder to a slightly different size that may give you a bit more line pressure at the wheels.