How do you split a 1959 Super Sailfish MKII deck?

I’ve seen reference to the way the factory would repair a loose foam block or other internal issue would entail splitting a deck from the hull, fixing then resealing. I’m still battling with a 1965 sunfish to get her split without too much damage at the joint, but with the Sunfish at least I can see the seam once I takes off the aluminum trim. My Sailfish only has a rolled over deck edge. Where do you split that?