ECU: No.
Gearbox: They are unsure.
Some 2L 8v have matching codes to your 1.8
Near the bell housing there is a code stamped, find it and find out about the donor engine's gearbox, if they match all is golden.
The ratios will be the same.
I personally reckon they'd fit, but really I guess there is only one way to make sure, and that's with codes.