How would an accretion / dilution model be different for a private seller?

The mechanics are the same, but the transaction structure is more likely to be an asset purchase or 338(h)(10) election; private sellers also don’t have Earnings Per Share so you would only project down to Net Income on the seller’s Income Statement.

Note that accretion/dilution makes no sense if you have a private buyer because private companies do not have Earnings Per Share.