What scale? If you're talking 1/72, a Redstone and the capsule are going to be pretty small, and I'm guessing you'll be stuck with an A engine. Will it take the weight of the resin? That will be a real issue in 1/48, I think. Will resin's weight in that scale screw up the CG? As long as you use a parachute and not a streamer, and sturdy plastic rather than a photoetched escape tower, you'll be OK I would guess. However, most of these Mercury kits I've seen lately have PE towers with them, which I don't think are very realistic since they are made of flat surfaces, rather than the proper round structural members. Now sure about Real Space's towers.
Your question reminds me of the old Estes kit from my childhood. I recall it was 1/48 scale, and unlike the later one with an all-injected plastic capsule, the old one had a balsa capsule. You had to create a jig and build the entire tower by cutting, sanding and gluing all different little lengths of wooden dowel, topped by the rocket motor section of the tower, which was made from a hard wood like the dowels. It was a real bear. Even the fins were difficult, with all their odd shapes, and sharp airfoils to be sanded in the balsa and assembled from about four parts per fin.
TOM