Dave -- You may or may not have read my post about it not being my first goat rodeo ---- and some comments I posted about a motors "rate of RPM"....
My 406 is done NASCAR style - Honda rod journal size - small rod end - with the reduction in reciprocating mass....
So check out the two dyno sheets comparing my longer arm 406 and the blown 383 - the FAR RIGHT column that shows RPM Rate of increase -- and compare it against the 383's.....
MY 406 8 stack:
The Blown 383:
