
This has been done for YEARS (especially in drag racing/class racing and circle track modified motors) and it does strengthen the rod (when done correctly). The stock casting line on the rods is a week point on the rod because when they were deburred from the factory they grind them sideways, this leaves grinding scratches across the rod. These scratches can make week points in the rod and points for cracks to start, and beings it is across the rod it is a short section for it to brake, the casting edges also are depressions areas that can cause week/stress points as it is not a consistent form/shape. When you grind off the casting line you do so keeping the new grinding lines the length of the rod, and the finer the finish the better. We always ground them to a mirror polish to start with then later years we would also go back and run them through the glass bead blaster to help release the stress off the surface of the rods. (a lot of new rods now days are shot penned for this purpose)
I myself, my dad, our buddy who has several Stock and Super Stock class records, did this for years on our motors, my 68 mustang still has the stock rods in it that I did this with and I built it in 95 and it turns 7,000 every weekend thousands of passes now.
It does strengthen the stock rod more then not doing it... However, yes it is not something you see much anymore as the invent of easier/readily available stronger aftermarket rods now days, and a lot of the stock class rules have been changed to allow aftermarket rods. Yes, you need to do your homework as to what kind of power your building and what parts will handle what, even then there is still no guarantee... that is why it is called racing

Also, Cast pistons are way heavier the Forged pistons. Cast pistons have a metal sleeve cast into the skirt of the piston to make them strong enough to handle the load (cast aluminum is not very strong) Forged pistons are exponentially stronger material and don't have to have this metal insert and are much lighter/stronger = easier on the rods = more Hp.
Anyway, I just wanted to help explain some soon to be forgotten old-school speed secretes (bb429power machinist must be old school enough to know) that are fast disappearing as today's tech is "buy parts and assemble them and go"...

bb429power: have fun with your build and keep learning some of the old tricks from that guy and others!
