Phil,
I looked up the stats for the scopes you mentioned. From what I can see, your TSA120 would be the better suited of the two, along with the 50mm EP. You might, just might squeeze in the whole of the disk, but I would say the Sun will fill the entire FOV.
Safety wise, according to the Daystar site, a UV/IR filter or a full aperture energy rejection filter be used for apertures over 80mm. I suggest you read the Daystar Quark pages carefully to best inform yourself:
http://www.daystarfilters.com/Quark.shtml
Steve Massey is also a great source of info as he has a lot more experience with the Quark than me.