Former Cygnus Air DC-8-73F is now with Transair Cargo as 3X-GHH.
No other DC-8's are left in Europe.
EU AOC must be no problem in most EU countries.
Most DC-8-70's which are avialable are the UPS fleet stored at Roswell.
In the US Boeing has two DC-8-70's for sale/lease through AerSale.
msn 46094 and msn 46029
Both former UPS a/c. Those are the best you can get if you want an airworthy 8.