I was reading through the thread from two years ago where he first tested the 270 heads.
The was no mention at the time, in that thread of the std M1 going on the 270 heads.

Doesn’t mean it didn’t get tried, but no mention of it in a 10 page thread.

If you read through all the articles he did with both the 240 and 270 heads...... the M1 gets sent out for porting while he’s still doing testing with the 240 heads...... and I dont see any mention of an unported M1 after that.

On the first 470 with 240 heads, the porting on the M1 was worth nearly 30hp.