I am VERY glad to see you taking this new route. Good form.
Yes, I would suggest looking into getting either permission for copying grips or if the rights to the designs are now free. But chances are even if a company is no longer making the product they still own rights to it. Contrary to popular belief just not making a product any more does not relegate the rights to it to the public domain.
As for design input…. The biggest issue I heard when making grips for Sheridan grip frames was that the originals were too small. With panels it is not very easy to add the bulk and have them feel right (because of the size of the frame itself), but with front wraps it is much easier to do. And I found most people preferred the front wraps. So that would be a direction to consider focusing on, although it is more complicated than panels. Feel free to shoot me off a PM or E-Mail if you would like to chat about it. I have considered this myself (and even have what I need to do it), but never gotten around to it. I have some ideas concerning removable insert panels and stuff that received good feedback when I discussed it with folks online and I would be more than happy to let you run with the ideas if you wanted.
Again, good form and I take my hat off to you for doing the right thing.