The question isn't how did he spread the frame, but did he widen the hub, and if so how.

If the OP didn't modify the wheel, it's already correctly dished (or should be) so changing the dish is not the correct approach.

Step one, confirm that the rim is correctly dished, namely centered between the axle locknut faces. There's no need to buy a special tool, he can use the FB/Campbell's dishing tool he already owns.

set three of the same* soup cans up on a table to form a tripod, supporting the rim at three points (no precision needed, just make a roughly equilateral triangle. Place wheel (tire off is better) on the cans, then stack up quarters from table to locknut. Flip wheel and compare the clearance to the coin stack (should be the same).

If the wheel is correctly dished, then the error is in the frame, and the OP can search "frame alignment" and take it from there.

*soup can be different as long as the can is the same.