To be certain, your'e gonna have to remove the flywheel and compare it to the illustration in post number 21. If the hole in question is in the same exact place relative to the crank bolt pattern, and is the size and depth as in that illustration, then indeed it is for a later cast crank.
But, I'll say it once more.... if you don't verify that the crank is cast or forged, you will be chasing your tail.
And again, please let us know what pistons are in there. Many non-stock pistons will not be balanced to the stock crank, cast or forged.
