well heres the easies way i would do it if i were u.. set up a pointer on the balancer.. i used a piece of mechanics wire that i bolted to the oil pan underneath.. take out #1 injector and make sure you are on the compression stroke of #1, not #6.. get a wooden dowl or piece of steel that is hair smaller than the injector tip.. make sure it's pretty long.. send it down in the head so it rests on top of the piston.. set up your dial indicator so it reads off of the top of the dowel.. make the dial indicator read .050 on the upstroke, make a mark on the balancer, make the dial indicator read .050 on the downstroke, make a mark on the balancer.. then find the middle of the two marks and that is your TDC mark.. time consuming, but most accurate..use a scribe or fine pencil, and a machinist rule to keep your measurements and marks as accurate as possible..
P.s.: Some pump shops will set the pump to factory timing, so it may be pinned at 12* btdc and meant to be put on an engine locked at TDC, you follow? that's what i bet happened.. A good pump shop will pin the pump at #1 port closing, so you can put the engine where ever you want in reference to the pump..