no, you can't add 1.75" coil spacers on top of the 2" lift springs. your springs won't have enough room to compress. you would need to extend the bumpstops 2" front and rear, on top of what you already have, to compensate. This will leave you with very little uptravel.
if you want more height, buy new springs, new shocks and everything else that goes along with 4" of lift....SYE, CV shaft, control arms, brake lines, sway bar links, etc.