I think a 1030 would be fine for it. I just built a new pc, so was thinking of putting the Dell in my son's room so he could play some games in there; but unless I get a good deal on the 1030 probably money better spent towards a newer full size GPU like an RX570 or GTX1650 Super or similar in the new pc.MY guess is any 75W half height card would work, unless it would refuse to fall back on PCE2.0 for some reason. The PSU is small enough I'm assuming you don't have a 6pin connector to run anything more powerful even if you could find one that would fit.
EDIT. apparently the SFF version is limited to 50W on the PCIe slot (page 16). If that's a hard limit you might be stuck with something like a 1030, because anyhing bigger will want 75W.