Given that you're set up for a flushometer, you would have to do some meaningful plumbing to go to a tank. As HJ points out, you have a full 1", well-pressurized pipe coming into your flushometer, and a typical tank toilet is looking for max 1/2", coming from a different location. So if you want to do a bunch of retiling and stuff, have at it, but it seems like a waste. Instead, you could get a nice Toto bowl and maybe a cool automatic flushometer or something, for not a lot of money. And an 11" rough-in is effectively a 10" rough-in because they only make 10" and 12" (and 14") toilets. 12" is now standard. And as HJ said, 10" is common for flushometer bowls.
Why not exploit the good, reliable flush that you get with a flushometer toilet and snazz it up a bit with cool hardware? Much cheaper than all the tile-breaking and plumbing you will need to do for a tank model.
Here are some ideas:
That's a Toto CT705ELNG (the "G" means it has Toto's CEFIONTECT (CeFiONtect) coating in the bowl, which helps a lot in keeping it nice and clean.
Spec sheet:
http://assets.nationalbuildersupply.com/ul_pdfs/toto-Spec-ct705elng.pdf
The street price on this is a lot less than MSRP, and should be just a bit more than $200, and about $40 less without the CEFIONTECT (same number without the "G"). It doesn't include the flushometer, and Toto makes a variety of them that look nice, from a simple manual one to the automatic one shown, priced well.
You could consider something like a TET6NC automatic valve, which you can get as a kit with associated parts included for under $450 (for the kit you add -32 to the number, so TET6GNC-32). It comes in polished chrome.
Or, for a nice manual valve, the TMT1LN32 kit can be had for around $175, and looks cool:
You obviously can use any elongated seat on this toilet's standard bolt hole placement, like a nice Toto SS114 softclose seat:
I don't know if you have a building plumber or your Super has a preferred plumber, but I can recommend a company that is licensed, bonded and insured that has done a bunch of work for us. Come on back with any questions, and let us know how it's going.