D6 what? It will have a serial number on the engine just below the head gasket line in front of the pony motor on the left side.
Mostly the timing won't ever change unless something breaks. It is set when the mag is installed so unless he has unbolted the whole mag, he should still be ok.
CAT has the points for most all the old magnetos so if those won't work, then get the ones that will. Clearance is usually set to between .016 and .018" with the points rub block on the highest spots of the cam. When its right it should throw a bright spark about a quarter inch to the block if you hold a wire near and spin the engine over.