The radiators mount differently, as do all of the underhood components.
I am assuming you mean radiator support when you say header panel, yes? There is a header panel in the 2nd gen, whereas the 1st gen. just has separate headlight buckets which attach to the support. You need that header panel for all of the frontmost parts. The more of the later radiator support below the headlight buckets that you use, the more fabricating you would have to do to mount your engine bay parts to that lower section. This includes the radiator itself, they mount much differently.
This applies to the side section also, the reason I suggest that you try to include the upper section, is to achieve a perfect fit of the fenders, in relation to the hood. To graft the parts would be difficult, yes, but if done right, then the front end parts would be very easy to bolt on, and align. The magic will be in locating the radiator support(top section) at the proper height, and forward distance.
If you properly cut and mock up the parts, screwing them together, or spotwelding, you can test fit the fenders and hood to assure a proper alignment.
I have a few of the pictures of my 93 Limited without a fender and front end. Give me an email address, so that I can send them to you. Regards,