Installing hydro notice cone on alpha. Oil drain hole is half a hole off (see pic). Should I grind the inside of the cone thinner on the bottom to rotate the cone rearward to improve alignment or elongate the drain hole to make it align that way?

Mine was right on. Hydromotive nose for Alpha pit on Alpha Gen 1.It fit like a glove, making install very easy.

Any casting flash or casting issues inside the cone not letting it fit better

In fact, by pretty good memory i think your cone looks different.

i guess i can dig out my old lower and see.

As far as your question, i’d make the hole on cone so you can access the screw normally. Fill the other part if the opening with all metal, which I used to mount nose cone to drive.

Can you take a pic of the cone by itself ?

Yup, that looks like same one.