one word of notice, I upgraded the firmware in my Multikit last weekend and it took one hour to erase that EPROM... (after three 10-minute passes there were still zero bits left here and there, so I cranked the dial up and also inserted the chip slightly crooked, when it finished I rotated it the other way and gave it another go without testing, so maybe 45 minutes are enough, who knows, still 3x as long as almost all my other EPROMs)
Maybe another... I only have a GALEP 4 which won't take 27C800s or 27C160s (this is the one in my version). The biggest my GALEP can take is the 27C240 which has a wildly different pinout, so I made an adapter with two dip switches for the higher addresses and split the image in two banks (as the image for the 160 is just the same data times two) and burned these one after the other. It works and now the machine only spits out about a second worth of garbage screens before displaying a nice splash screen (while it's loading and decompressing the rest of the data into memory) and going into the menu. If your monitor is quick enough, you might catch a glimpse at the splash screen, I think it looks pretty cool!
(and another... the Test Tape sits on a black screen for maybe about a minute before anything visibly happens - it tests the 48k of RMS3 RAM before doing anything - and it waits for the Credit Switch to advance the test)