hello ford econoline friends

Have a big issue with my e150 1997 ,the valve is leaking and because the motor have made around 300.000 miles it is not worth the effort to rebuild the heads .It is stil running but it is using gas and doesnt run very good ..it used to run very smooth and it was a pleasure to drive my van .Now it is since december 2016 by a mechanic .. my question is who want to sell a good engine ?? it must fit in a 97 e150 econoline it used to be a 4,6 engine but i prefer engine from 350 or 250 .. iam located in Netherlands europe so it needs to be crated and shipped to amsterdam iam not rich i cant pay a new engine so iam look for a low mileage good runnin reliable engine no suprises thank you Hope i can drive soon in my Van again