Hey there;
In my area at least, most of the parts stores have a tool loan program. Tools like; pullers, brake piston reset and possible a flaring tool may be available. The only other suggestion I would have, aside from purchasing one, would be to take the brake line down to a local shop and see if they would flare it for you. As long as you have an accurate measurement for where the flare needs to be... could go either way

Keep posting!
Looking good.
Steve

1946 Chev 1/2 ton - 6V/+ground/Bias-ply original - shake/Rattle and Roll! (SOLD)
1940 Chev 1/2 ton Franken/Restomod