I am running an 11-34 IRD 10-sp cassette with a 105 double FD and an XTR long cage RD and it works fine.

If you already have the 105 RD, then try it and it might work. Don't buy one, though, as it is not adequate for the job, specs-wise. I don't remember the particulars, but I did not go willingly to an mtb RD for a road bike, except no road components were supposed to work (road cassettes are not that big, as you know)