Are there areas that transition from very thin to very thick? That creates an inherent problem, as resin does shrink when it cures (if even an infinitessimal amount) and that will cause warpage (similar to permanently warped acetate promos; you can "fix" those temporarily but they will soon pick up their "normal" warped shape).
You can try grinding the hood to a consistent thickness and then bend it back, then add stiff wire underneath as bracing. This could be located where it can be covered by underhood bracing detail.
Only other way out would be to construct new hoods using the original kit hood, plastic in the needed shapes to reconfigure it (vacuum formed if needed), and epoxy putty. No solvent cement, no two-part glazing putty, nothing that dissolves the plastic, nothing that catalyzes "hot".
--Mark