With due respect, if you haven't defined your cargo market both ways, then you shouldn't have determined the airframe. Requirement needs to come first with a decent yield. You will need to be getting an incredibly high rate westbound as 30tonnes of freight anywhere US to anywhere Europe will generate max $1.00/kg plus fuel/war surcharges which won't pay the costs. If you have to tech stop anywhere then you'll be bleeding to death very quickly.
If you do find the "golden" freight westbound, then if the majors don't know about it (unlikely) then they soon will and everyone will compete for it driving the yield down well below your costs. Pax upstairs means freight downstairs can be carried cheaply.
In the meantime, ask a decent Cargo GSA in the USA to run the eastbound numbers for you.
A-Z Airfreight Directory - Airlines´ General Sales Agents - United States
Good luck
MF