I picked up a cheap woodie coffin-type plane a bit ago and am
considering making it into a scrub.

How does one grind the camber into the iron?  It's, naturally, ground
straight right now.  I'm not above using electrons for this, but is it
sufficient for a scrub to mark the curve I want, then freehand it on
the grinder, then sharpen?  Seems it would be, but wanted to get some
more learned opinions.