A calf injury kept the experienced lock out of Scotland's opening two games of this year's Six Nations and they lost badly in Wales before returning last weekend with a home victory over France.
Coach Gregor Townsend said on Friday there would be more clarity at the weekend over the availability of Gray, who last played for Scotland in last year's Calcutta Cup match at Twickenham, which England won 61-21.
Fargeson and Nel were also missing through injury for the last two internationals with Scotland having four props and two hookers out through injury or suspension at the start of this year's Six Nations.
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Simon Berghan has since returned from suspension and having Fargeson and Nel back will add to Townsend's options before next Saturday's clash at Murrayfield.
"It's a huge boost to have those experienced players in similar positions," the coach told reporters.
(Reporting by Mark Gleeson, editing by Clare Lovell)
