4X4 upgrade

Absolutely not. I saw a friend try this with an older 1980's model, and it ended up in his front yard with a "for sale as Is" sign in the window. You have the additional burden of numerous computer controls, and their inter-connected wiring harnesses to contend with. Even the instrument cluster will be different. Most likely the frame will be different with different cross members to accommodate the transfer case and different drive shafts. The floor sheet metal is different for the shift lever and transfer case. The front axle for that year is a solid tube design with coil springs. The two-wheel-drive version uses upper and lower control arms to hold the spindles. You would need to cut off those attaching ears and weld on all new hardware ad brackets.

Look at this as an opportunity to buy what you want. Do not try to build one yourself. Use a site like that for Rock Auto to see how few steering and suspension parts are the same between the two models. You will have three times the dollars in parts before you give up as it would cost to buy a good used truck.

Is it "possible" sure, with time and money, anything is possible.
However, is it something that can be done easily or without tearing apart most of two vehicles to complete? Nope.
As Doc said, the frames are different between the 2WD and the 4WD.
About the only way to do this would be to take another Suburban with the correct running gear and options, remove that trucks body and bolt yours on after replacing the 2WD front floor pan with the one for the 4WD. But if you are doing that you may as well just sell the one you have and buy a 4X4 Suburban to begin with because after you do all that the end result will be worth less money than either of the vehicles you started with.