Wow, rebuilding the whole engine to get a forged crank simply to accomodate a 4 spd swap is a little extreme, dontcha think?
We all know forged cranks are better, but they may not necessarily be a requirement for this application. Nobody has even asked what the car is used for to see if the expense is justified. IMO, if this is simply a weekend cruiser, get an offset balanced flywheel, slap it on, and get on with the swap. Will it be perfect, no, but if we aren't dealing with a competition car, we may be splitting hairs that may not matter.