I've not tried one with Type 54 film. I've used Type 56, though, the sepia film, and I've had to alter the standard process for lifts when I use this film.
I can tell you what I've done differently and maybe one or more of these tricks will help with the 54. But I make no promises!
First off, I found that if I leave the white border on the print, I can boil it away till the cows come home, and that emulsion is NOT going to budge. Solution: with sharp scissors, trim off every bit of the white border before you start.
Second: I used boiling water, like you did - and the print DID curl up. I had a pair of tongs in each hand, and very carefully kept pushing the print so it would glide through the water, from one side of the skillet to the next, and it would flatten naturally while it was gliding, helping the emulsion to lift on its own. Push it back and forth several times, the emulsion starts lifting on its own. It sounds a bit awkward, since you no longer have that bit of white border to grab, but keep trying, it does work and it gets easier.

Keep the water level somewhat deep to make the gliding process easier and keep the emulsion immersed, even while curled up.
Oh, and I also found it was wasted effort to cover the back of the sepia film with Contac paper (the vinyl adhesive paper) since the boiling water took it off in about 10 seconds. :LOL: So that actually saves a step.
Once the emulsion is floating free I cut the heat, grab the emulsion with the tongs and flip it into the cold water bath. I no longer bother with the mylar sheet - I slip my receptor sheet (generally watercolor paper) right into the cold water and under the emulsion and capture it that way.
Once I'm done with designing the lift, I use a wet brayer and gently pass it over the emulsion, using no more pressure than the weight of the brayer itself, to squeeze out air bubbles and excess water.
Hope this helps.
