Fuggles will be fine in an amber ale. Willamette is basically fuggles grown in the US... basically.
My house amber I add a 60 min addition of fuggles to around 30IBU, then 40g fuggles dryhopped. This is NOT like JSAA though!! Dryhopped fuggles are something that aren't to everyones taste (as demonstrated when I swapped my amber!), but I absolutely love them. For a JSAA, I'd go a 60 min addition, then maybe 20g @ 10mins. A very small dry hop, say, 10g, would also help to give it the "classic" JSAA aroma.
Any recipe looking to be like JSAA should have a little chocolate malt added to it also IMO. Not much - 50 to 80g.
My house AG version is something like
3.5kg pale malt
200g medium crystal
400g cara-amber
80g chocolate malt
40g fuggles @ 60
40g fuggles dryhopped
US-05 yeast, fermented around 17, then ramped up to 21 as it begins to slow.
For you, I'd just sub out the pale malt for LDME - no idea on numbers, just whatever will get your OG to 1.045-1.050, and change the dryhop to 20g fuggles @ 10 and 10g fuggles dryhopped. If you don't have cara-amber, you can leave it out - body is not really an issue when using lots of LDME, and colour should be right enough with just the crystal and chocolate. Chocolate malt and medium crystal though are must haves for any extract brewer
It won't get you exact, but it will be closeish.
And of course, when thinking about JSAA, you have to ask whether you want the classic version - malty, spicey, with just enough roast to keep you interested - or the new version - soggy bread.