Does this prove David Vizard's 128 lsa formula ?

Ant,
Get DVs SB Chevy book, SA books #57. Money well spent.

It has a couple of pages of cams, hyd & solids, FTs & rollers, from mild to wild, for various engine sizes. It gives LSA & duration for these cams & you will be able to make an INFORMED decision on a cam for your engine.

I believe 273 touched on this earlier & I am not sure if it is in this book or his BBC book: if you want more low end or smoother idle, do NOT widen the LSA, reduce the duration.