Hector
For about 10 years I worked for an air tanker operation and for about 6 of those years we operated eight A-26s.
The pictures in the sites that John P reccommends give you a good look at the wiring system for the ignition. However, in all the pictures, the Bendix mag is installed. The two round objects at the top of the nose case are the distributors and the large black object between them is the magneto. In otherwords a single magneto with two distributors (They are a real pain in the rear to time to the engine). The -21 version has this type of ignition.
However all the A-26s I have seen or worked on, were equipped with the -71 version of the R-2800. The only difference between the two dashes are the magnetos installed, with the -71 having GE mags instead of Bendix. The GE system consists of two seperate magneto/distributor units with the central mag location covered with a plate.
The shape is rather hard to describe as they are not round or square but somewhat heart shaped with two hook shaped arms at the back to plug into the ignition harness. GE mags much easier to install and maintain. Also note in the WPAFB photos, just forward of the magneto, there is a square plate. On the -71s we operated the propellor govenor was located there with the control line running back between the magnetos and between the #2 and #14 cylinders.
The exhaust presents some problems. Unlike other radial engine installations (P-47, F4U, B-26 etc) which used a "ring/modified ring" exhaust, the A-26 used 9 "jet" exhausts, each a single piece unit serving 1 front cylinder and 1 rear cylinder. Four exhaust ports on each unit was vented aft, just below and slightly aft of the cowl flaps. Closest thing I have seen resembling it is the FW190 system. They attached with clamps to the cylinder exhaust pipe on the rear cylinder and, until we fabricated a simple reinforcement system utilizing a 2" exhaust clamp and a 6" strap to the rear cylinder head, they gave us fits. Between vibration and backfires, sooner or later you would look up and where there was supposed to be an exhaust pipe, there would just an empty space under the cowl flaps. Followed by about 8 hrs of really hard work replacing the rear row cylinder. Seems the exhaust pipe on that cylinder always pulled out, so it had to be replaced.
Other than an A-26 maintenance manual, not sure where you will find a picture of the system.
Wow - got a little long winded, but hope it helps