The board will fit, but you have to take very much care of it as to what isolating it matters, any contact with the parts in the motherboard will fry the a1200 mobo or the delfina itself.
I expected that. It's a shame the Delfina 1200 isn't for sale anymore. It would be a better fit.
You will have to remove the metal shielding inside the A1200 to make it fit properly.
This is long gone... :-)
One more thing you must be aware of is that you have to make it fit so that you have access to the RCA type audio outputs of the board (maybe using a cable to access it and getting that cable out of the machine via the rear trapdoor of the 1200 near the mouse port).
The rear trapdoor of my A1200 is used up by the Blizzard SCSI controller. I expect to have to make a hole in the upper backside of the A1200 for the in/outputs.
The same for inputs.. (the board does NOT have RCA type inputs), all inputs are cdrom-audio-like ports/connectors.
Still in doubt between a Delfina- and a Subwaycard... The chances of both cards fitting in the A1200 are pretty slim, I expect, not even mentioning my poor PSU. Decisions, decisions... Sigh... ;-)
Maybe it's smarter to go for the Subway and wait for a secondhand Delfina 1200 to surface somewhere/somewhen.