Go with the foam material that Jon Goodman sells. It is of a type that will not go gummy in another 20 years. His "kits" for general rehabilitation contain several thicknesses and densities of material for applications ranging from door seals to mirror damper.
So far, I have rehabbed about 40 RB Pro and Pro S backs. You have a very messy project in front of you, and the thin seal on the insert is much easier to place using material that does not have adhesive--Jon's kit has precut strips that are great for this. Glueing these two thinline seals on the ends is sufficient. The ones that go on the back itself are not too difficult. Be sure that you do not use too thick a material along the hinge section.
You will need denatured alcohol, acetone, contact cement, the bamboo tool that comes with the kit, a dental pick, toothbrush, small sable brush, surgical scissors, tweezers, a very sharp X-Acto knife, metal straight edge, cutting board, some shop rags, a syringe to apply alcohol, and a great deal of patience with your first one... You will find that getting the self-adhesive strips into the back channel without them catching on the side and rolling about is somewhat challenging! You must also cut these strips yourself, as the material kit does not have but one size of precut, non-adhesive material. That is too narrow for the back... Foam material at the thin widths you need cannot be cut right with a scissors (only the end cuts), you must place the foam side down, line out the width with your straightedge, apply pressure (careful, as too much will create a beveled cut) and cut in two smooth passes. When filling the channels, do not premeasure an exact length. Always make it longer, and cut to fit once the bulk is placed and tamped down. Otherwise, you can be short and cause a light leak. The same goes with cutting where one seal butts against another.
The corner sections on the insert can be a little tricky. Here, make sure that you use a thick enough material...
