Confirmed that the first zlib block is indeed the save image:

I didn't bother loading up the menu palette for that render, so that's just a sixteen-color grayscale palette. The format is a simple bitmap, with each byte ranging in value from 0 to 15 and representing (in reverse order) a color on the 128-143 palette line.

ETA: The sixth/final zlib block is the triggers, it's a 32 bit string of zeroes (off) and ones (on). The fifth/penultimate is the dictionary, equivalent to Data3 in a .j2l file and seemingly using the exact same format. The second block seems to contain general info and is always 1444 bytes long. The fourth block is (width*height*4) bytes long, and looks to be the event map, with the otherwise-ignored fourth parameter bit (between difficulty/illuminate and the custom parameters) representing whether the object exists (1) or not (0). Zones, of course, leave this at 0. This event map is read in place of the one stored in the actual .j2l if you die, but is not read at the actual event of loading and will not itself add the sprites it needs.

ETA2: Ammo is stored in the second block, starting at offset 1024. First there are nine longs representing ammo (blaster seems to start at 100; Toaster maxes out at 3168 instead of 99, because it depletes more slowly), then nine 0/1 bytes for whether the gun is powered-up or not. Lives are in the same block at offset 416. Score is two longs starting at offset 968; I assume one is the real score and the other is the score it's displaying, which may or may not have finished adding up to the real score. Sugar rush duration is at 1212; shield id (only 01 through 04 have bullets) at 1132 and shield duration at 1136. Health is at 62 and you will die on loading if it's set to 0, forcing the game to load the event map in the fourth block.

ETA3: In the main file, the uncompressed data between the third and fourth zlib blocks is a long (minimum of 1), followed by (long-1) units (either longs of value 0 or strings of 128 bytes), representing objects current in memory:
ETA4: Oh, huh, these are some pretty familiar numbers right here.