+3 for Wiseco. For a frankenbuggy donor, I would always go forged. The forged kits are affordable and seem to last a long time. Dirt bike riders at the shop go both directions with these, the forged are less likely to distort, but the namura has a coating on the skirts that helps with cold starts.
If you don't mind, could you snap a pic or two of the gearbox? I have a trailblazer FNR box with the same chain damage. I am mostly looking for mounting tabs and orientation of the box in the frame.