Doing the big 3... should I ground from the alt casing to batt- or from engine block

[quackhead 10+ year member]

Electrically speaking, alt casing and engine block are the same piece of gear.

lol...exactly...the engine block to body/frame(wherever batt is grounded) is this upgrade. I suppose you can do it like OP too, but as he found out, usually a longer bolt will be required, and in many cases there is not enough room for the longer bolt/wiring.