The math: maximum offset = old journal - new journal.
Stroke change: offset (- .005" or so for the grinder to spark out unless the crank is new)
2.375" (B/RB) - 2.20" (BBC) = .175" max
3.75 + .170" = 3.92" max
You can have any stroke change between - the offset to + the offset.

[Please note: it's not the offset X 2]

Boffin Emeritus