As far as parts and stuff go, just cruise by JimZ's website and download the plans. In the plans, the two BT55 body tubes for the main airframe are each 18" long (for a total airframe length, minus the nose cone, of 36".)
For mine, a made the following changes for finishability.
First, you'll notice on the paint scheme in the plans that the lower 15" of the rocket is painted white, the remainder above painted blue. To eliminate or mask the appearance of the joint between the two BT55 body tubes, I used a 15" body tube and a 21" body tube rather than two 18's. This allowed me to attach the fins, sand and seal them, etc. on a very manageable 15" length of body tube; as well as paint the white portion of the rocket separately from the blue to avoid any masking at all. In fact, I applied all the decals to the white portion before coupling the blue portion to it, because that shorter length was easy to manage on my build table. The result was a very sharp white/blue interface that masks the bt joint.
Secondly, I used a stuffer tube. This wasn't so much to aid in recovery as it was to provide additional rigidity to the airframe. I used a 24" length of BT50 for this tube. It is mounted flush with the bottom of the rocket on the motor end (as per the plans) and it extends 9" into the upper or blue tube. This leaves 12" above the stuffer for the "laundry" and after having been all epoxied together it gives a lot more rigidity than the simple 2" long BT55 tube coupler at the airframe joint. A kevlar shock cord anchor is attached to the top end of the stuffer. The engine hook and engine block are sized to accomodate "E" engines, D's with a spacer. This is also a change from plan.
Also, I relocated the launch lugs from the plan. Well, first I upsized them to 3/16" lugs just out of preference - not sure if it's needed. But on a taller rocket under "E" power, I went with the maxi-lug. Anyway: the plans called for two pieces of launch lug. The top one mounted flush with the top of the lower body tube (in the plans) and the bottom of the bottom lug mounted flush with the bottom set of fins at their attachement line to the body tube. These lugs are mounted on a line that is centered between a pair of fins, which is standard Estes build stuff.
That was the plan. In mine, my body tube was shorter, so to mount the upper lug in the exact same location as the plan, I would have had to mount it 3" above the bottom of the blue tube. This seemed like a pain in the butt since I was building and painting the upper and lower halves separately, so I went ahead and mounted the upper lug at the top of the white tube, which is 3" lower than plan.
Also, looking at the finish of the rocket, when it is set up like in the first pic I posted, the name "Blue Bird Zero" is centered between a pair of fins. The two lowest fins in that pic have decals on them, the third fin on the bottom (which is pointed at the wall and not seen in that picture) has no decals. If the launch lugs are mounted between a pair of fins (like the name Blue bird Zero is, but around the back between a different pair) you could see the lugs when the rocke is viewed from the angle posted. For no other reason than personal preference, this annoyed me. So, I nested the lower launch lug right into the joint of the lower fin and the body tube. Right up against that fin with no decals on it. Then I just lined up the upper lug with the lower. To me, this just gives a "cleaner" look.
Don't forget to get your decals from Astronboy - they're excellent!