Having gone through the 54 windshield install I would suggest that you shop around and find someone who has successfully installed a one-piece 54 windshield.
If by chance you have a stainless steel trim piece in the rubber gasket I would make that mandatory. Secondly, I would use only a Steele windshield gasket. If you do have the s/s trim it must be installed in the gasket before the windshield is seated as it plays a roll in seating the gasket properly against the pinch moulding.
After using a well known glass company for my initial install, I discovered that there was an air-gap that poured water into the cab. My second attempt required another major company with a 3 person crew.....the lead guy was experienced with the 54 truck specifically and the other two were glass company employees. The actual installation took 3 hours....one to get it seated and the other two to clean up the sealer. And they couldn't get the S/S trim to lay flat all the way around. Because of this I had to add some sealer after-the-fact to fully seal the glass.
If I had it to do again I'd hire it done by some experienced glass installers.....I'd use the Steele gasket and personally test it with a hose the next day after the sealer cured. It was a month before I discovered the little leak. Cabs get twisted and the glass may even need to be ground on the edges for a perfect fit. All it takes is one little leak to cause you grief!!!
Dave