well as long as you have crit and some wisdom your urgent heal will still be really high. higher tiered staff/magic damage will help as well. however if you want your heals to be high you are going to nerf you damage, there is no way around it.
if you really want this kind of thing, keep 2 sets of gear and switch them every time you want to throw some heals out (note you should have the same amount of hp, because each time you switch gear, your hp will only be as high as the lowest hp gear, for example if you have 60k hp on your mage and then you have 50k hp on your priest gear, when you switch from priest to mage you will only have 50/60k hp.
anyway this is all really expensive. you could always try the vahtos set which will increase magic power by 15%, but by veering away from all the ghost stats you get from purple accessories it doesnt really seem worth it