I guess that I am a grumpy old man this morning
I have been a proponent of the metric system my entire adult life, but, while I understand the work that went into this post, I do not understand the need.
I have yet to see a factory Chevrolet parts book that listed a 3.851 litre engine. And while I will confess to stopping at 1974, not a single one of the literally thousands of original and aftermarket references in my library refer to a Chevrolet 3.851 litre engine.
(1) You can pretty well guess the origin of any current parts for a 3.851 litre engine, and it is not "Made in U.S.A.".
(2) If one calls The Carburetor Shop asking for a carburetor or a carburetor rebuilding kit for a Chevrolet 3.851 litre engine, I will guarantee we don't have any; although we have dozens of carburetors for a Chevrolet 235, and manufacture kits (in the USA) for every original Chevrolet 235 carburetor.
I get enough "revisionist history" from the politicians; I do not need it in my business.
Like I said, maybe a little grumpy this morning.
EDIT: and in a different lifetime (a skosh over 50 years ago, I lived in Japan, and actually thought metric), and still am able to do a mathematical conversion, if one were necessary!