Well, a mechanical pump generally gets timed "by ear" as most people don't have access to the proper tool to time it. It basically uses a timing light deal that picks up the pulse from the # inj . 6.5's AFAIK have an adaptor to clamp onto by the IP. The older 6.2's don't that I have ver seen. Kent moore made a tmiing light for doing this but good luck finding one. Snap On also had the MT480, again good luck finding one with the prper adaptor/probe. Most 6.x engines I have ever worked on with the DB2 usually end up with the mark on the IP about a matchbook cover to the drivers side from the mark on the case cover unless you can find the timing light to do it properly. There may be other tools that can do it but as far as I have seen I am only aware of the Snap On and Kent Moore, both of which are obsolete and no longer in production.
The engine should start good and sound a little marlbly.. If the motor is too quiet it may be retarded, if it's really loud may be too advanced.