Kenny, if I see that correctly, all it is, is the ramp for the advance lever is loose. It is as simple as tightening it up with a torx wrench (usually a torx). Set it up, with the throttle at its idle stop, and bring the ramp to the point, just before it begins moving the lever. It is just cast aluminium, and can break easily if over-tightened. Hopefully this is the problem. If it is cracked, the ramp (rocker lever cam plate) is interchangeable from any DB2831 series pumps. Part#29122. This would explain a lot of things with your timing, as the lever is there to bleed off some of the pressure acting on the advance piston, to retard (or limit over-advancing) some what as rpm's increase.
as for the injectors and lines being different, they are in the sense that the 6.2l N/A spec lines are actually a bigger I.D diameter than 6.5l lines( we have measured all the lines that have been used through the years, no one else has to date proven otherwise) and the injectors, well, the 6.2l 253 nozzles actually are bigger than any other used( we have measured ID of every injector nozzle style ever used in these engines as well), including "marine" ones, the only difference being the marines use a stubbier needle than all others( while the ID of the nozzle is the same as the 304's), giving more low RPM fueling potential, other than that its the difference of pop pressures, and physical appearance, IE long and short.... sounds like metro diesel would hate us when we told them they were crooks... LOL... they are taking you for a ride....:shake: