The supply variety on ECL parts in general has ever been diminishing over the years, the variety is not even continuous. I should now connect an FPGA to a bunch of ECLs. The LVDS to LVPECL translation can be done with a 65LVDS100. Further I can only find a few ECL parts and finally I should connect to LVPECL again. I consider now lowering the Vcc for the PECL to 3.3V and set the associated GND to -1.9V for a blunt signal connection. The signals of (LV)ECL in general are referenced to the respective Vcc, so this should be doable.
FPGA-LVDS -> 65LVDS100(3.3V,0V) -> PECL (+3.3V,-1.9V) -> LVPECL(3.3V,0V)
Differential signal may have less problems than single ended in this configuration, I guess. A one point I'll have to go single ended though.
Rene