Some thought to get you started Macqyver!
Some upper ball joints, aren't that hard to press in and out. You may find a few large C clamps get the job done. Both in and out.
Key is when pressing in, press in squarly. If you get ball joints off, so one side in deeper than other, during pressing in. It will bind and be a beast to press in.
I fear living in a jungle, you've excessive rust. Which rust can be a PITA to deal with, causing ball joint to be frozen in. If you take off UCA, and soak ball joint end in old transmission fluid for a few days. It will loosen the rust. You can than remove boot and lock ring, locking in ball joint. Place a large socket/metal receiver cup over ball joint as a solid brace to drive ball joint into. Pound it out. Key is solid surface to pound into, holding control arm without any flex.
Press in UBJ, on the bench (UCA off): Clean the hole ball joint fits into. Lube receiver hole with grease. If you have a large vise, and something to use as a receive cup for ball joint, holding UCA solidly. You'll press in easily. If not, you may rig sometime using your jack and weight of vehicle as backstop (hold UCA firmly). Which receiver cup, is anything that holds control arm firmly, as you press or tap in ball joint. Even using some point of frame, where you can get control arm to hold in place. Places that come to mind, are frame to cross-member corners, which you'll fine a few points where frame meets a cross-member. Than use jack to press ball joint up into LCA, while LCA held in place against frame. You can also tap in ball joint with care. Just avoid pounding directly on ball joint with steel to steel, if you can. Using brass hammer is one good option, or brass plate, rod, etc.. Or place a flat steel plaste on ball joint, to pound on to.The key is solid receiver cup while pressing or tapping in, all power goes into ball joint. If your receiver ( UCA) is moving or flexing, you loose power.
I can't stress enough. The key is ball joint is lined up squarly as yo press in. If it gets cocked at angle, while pressing in. Stop pry out and start again.
Have fun!