Congratulations on getting your problems fixed! I'm sure you learned a lot in the process.
I am about to change out my OPDA. Do you have a sense of how and when things went awry?
Not certain exactly what happened but here are some thoughts about what seemed to be potential problems.
1. Probably should have removed the plastic pin from the Crown and used it to pin the OEM OPDA as it would have provided an OPDA removal with less play. I believe the slack left the slot for the oil pump drive in a position so the Crown would not seat on the base.
2.Tried to force the Crown by twisting with more force.
3. Was to late to realize that the oil pump slot could be move a small amount to achieve alignment.
4.*** Pretty sure I tried reinstalling the OEM to try to realign the holes. Had been at it a while and should have quit. By the time I finished on the first start up the engine would only barely run for a few seconds and produced a couple of backfires. I may have at one point tried to turn the crankshaft to align the new OPDA with the oil pump slot. Pretty safe to say probably didn't miss any mistakes.
Sorry I don't have better info but I tried so many things I know I have forgotten some and probably confused on others.
If I were to do another one I would use either the plastic pin from the Crown or an allen wrench that provided a close fit when pinning the OEM OPDA.
One of the things I do not understand is, I had to find TDC of number 1 to get my unit to work. So does that mean when the unit OEM unit is pinned the number 1 is TDC? And if so how is on compression instead of exhaust TDC, when as I understand it must be on TDC compression. I think know the answer but maybe potential confusion might be avoided if one of the members respondes to this.
Best of luck on your install. Don't rush or force it and you should be fine.