I have to replace my rear wheel cylinders - the fun never stops with a Morgan does it

I've found this
thread that discusses the steps but before I get too far I wanted to ask for help on how to remove the backplates.
From the discussion and diagram it appears that there are 3 plates on the rear and per Guten's comments I need to follow these steps :
"One of the clips has little lugs on the end, before you remove them check where these are so you can get them back the same. Prize the one clip over these as you pull the other one out. Make sure when you replace them the lugs lock over. The clips are bent to form a spring, take note which way they are as you take them off."
Before I get too far I was hoping that somebody could confirm that for the first plate, the retaining plate, I can just prize off with a flathead screw driver.
I've seen articles confirming that with 1993+ models you can replace the cylinder without removing the brake shoes - I also wanted to confirm that this is the case with earlier models before I get in too much trouble.
Thank you !