回答
this is not a piece of advice to you I'm talking to myself for my practice of writing skills.
I've tried to put your sentence into GT. GT's translation is the next sentence.
it is valuable as an antique. (GT's translation J to E)
it has a value as an antique.
it is worth as an antique.
it has a worth as an antique.
it has the antique value.
it has the antique worth.
I suppose verious expressions might be possible.
I'm sorry I can't undrstand the natural expression. I have a belief that the sentence would be comprehended if GT could translate. but I'm not sure it's natural or not. as a reference only.
:GT.
https://translate.google.co.jp/?hl=ja&sl=en&tl=ja&op=translate
:worth. on the weblio.
https://ejje.weblio.jp/content/worth
:antique. on the weblio.
https://ejje.weblio.jp/content/antique