The Fantastic Four #4: The Newton edition

Newton Comics' The Fantastic Four #4 was published 16 August 1975:

The cover is recoloured from Marvel Comics' Fantastic Four #5:

The story contents:

Prisoners of Doctor Doom!, originally published in Fantastic Four #5, July 1962

[Prisoners of Doctor Doom!] Part 2 Back to the Past!, originally published in Fantastic Four #5, July 1962

[Prisoners of Doctor Doom! Part 3 On the Trail of Blackbeard, originally published in Fantastic Four #5, July 1962

[Prisoners of Doctor Doom! Part 4 Battle!, originally published in Fantastic Four #5, July 1962

[Prisoners of Doctor Doom! Part 5 The Vengeance of Doctor Doom!, originally published in Fantastic Four #5, July 1962

The Human Torch Meets Paste-Pot Pete!, originally published in Strange Tales #104, January 1963 

This issue contains a Silver Surfer poster:

This poster advertises the forthcoming Silver Surfer series. This image is from the cover of Marvel's The Silver Surfer #7 and was on the cover of Newton's The Silver Surfer #6.

This issue includes an inhouse ad for The Amazing Spider-Man #6:

The favour was reciprocated: The Fantastic Four #4 was advertised in The Amazing Spider-Man #6:

This issue includes a subscription page, A Super Hero Tee Shirts offer, a Marvel Mailbag page, and a contest with the expiry date 29 September 1975.

The publication date 16 August 1975 is a guestimate but I'm confident it's accurate based on available information.