There are actually 3 different ED variants in the years your looking at.
There was a small run of initial release ED's in '87. these came with dark grey front and rear bumpers.
Then the...
If you have an original EF9 then leave it as-is as it'll be worth more later.
To fulfull your burning desire to build a track whore then buy a local ED6 and go mad with that.
JDM tags are not encoded, one of mine reads EF8-10000xxx. So if you knew which factory the EF2 was made (Suzuka plant? Where the EF8's popped out perhaps?) and you found out how many they made a year...