If the upper tubes are bent, you might want to remove the trees and check them for straightness.
Take the lower tree and place it on a flat surface, like a table top. Use a c-clamp and clamp the trre to the table where the fork tube coms through it. look at the eother side where the fork goes. Is it flat on the table? Move the clamp to the other side. Does the first side set flat on the table?
If not then you need the trees too.
Try taking your original forks apart. Take the tubes to a good bike shop, one that deals with dirt bikes. They can straighten them for you if not bent too bad.
Once you get the fork right, you need to check the frame for straightness to. Get the forks and wheel back on. Get the rar wheel straight in the swingarm. Measure from center of axle to center of swingarm pivot bolt. Get them the same both sides.Now with two straight edges long enough to reach from the behind the rear tire to in front of the front whell. set the straight edges against the rear tire so it touches it front and rear.
The straight edges should be equal distances away from the front and rear of the front tire and be the same front to back.
Leo