Nick,
I wish you well in your quest. You may have some luck as the items you requested were 'boxed' items and not strarter set models. I have seen too many examples over the years spoiled by their press-apply stickers being desroyed by sticking to the clear covering on the LGB box lid, in the Amtrak guise and the two 'LCE' variations. The Amtrak version comes up reasonably regularly on U.S. eBay but is generally limited to only the power cars and single intermediate car. Single Amtrak cars are eagewrly sought after.
I am not gloating as it took me many years, but I have a ten car Amtrak LCE, an eight car original LCE train and a six car latest release LCE (plus several power cars). Among all my LGB, these LCE variants are my favourite. About four years ago I sold off a six car Amtrak train with twin motored power cars and regret each day since doing so.