Trying to translate a part of the Lay of Leithian into sindarin

I'm trying to translate these lines specifically: (Canto II, about Morgoth)

"Far in the Northern hills of stone,

in caverns black there was a throne.

A king there sat, most dark and fell

of all that under heaven dwell.

Than earth or sea, than moon or star,

more ancient was he, mightier far

of strength primeval, ere the stone

was hewn to build the world; alone

he walked in darkness, fierce and dire,

burned, as he wielded it, by fire."

I am by no means an expert, but I have attempted translating this into Sindarin and establishing some sort of rhyming scheme to match the rhythmic style of the original text. Here's what I offer:

Haer v’in eryd ‘ond fyrn,
Arahadhw v’i phelig vyrn.

Ennas hant aran dhur a naer
Pain i dhorthar nu Menel.
Te iaur thar Geven a gaear,
Te beleg thar Ithil ah êl

Ir i ‘ond law dhrammen sîr
gared Amar; na vellas iaur
Balch a daer, vi vôr pant îr
Maethant den, orthant di naur.

Hope this helps. If someone more knowledgeable could please check this over, that would be great!