Newton Comics' The Fantastic Four #1: Querying the publication date and the cover

Here's a cover scan of my copy of Newton Comics' The Fantastic Four #1:

Here's a scan of a pre-production advertisement for The Fantastic Four #1 as it appears in Newton Comics' Planet of the Apes #1:

As you can see it is the same image albeit with somewhat lower resolution and cropping on the right hand side. The difference between the two is in the text overlays and the caption boxes. 

The advertisement announces an on sale date of 14 June. The 14 appears to have different characteristics to the rest of the date related text. 

I date Planet of the Apes #1 as released on or before 7 June 1975. The competition on the rear cover expires 7 July 1975. However, the competition on the rear cover of The Fantastic Four #1 expires earlier, on 30 June 1975. In the normal sequence of events the competition on The Fantastic Four #1 would expire shortly after the competition in Planet of the Apes #1. I also note that my date for the release of The Fantastic Four #2 is 12 July 1975. In this initial stage of their publication program Newton Comics published their titles fortnightly. The pre-production advertisement, the out of sync competition dates and the July date for The Fantastic Four #2 all suggest there was a delay in the publication of The Fantastic Four #1 on 14 June 1975. I haven't checked the editorial notes in the letter columns for more information in this regard, but will update this note should pertinent information come to hand.

Something else of interest - see below a scan of the original Marvel cover to The Fantastic Four #1:

Quite apart from the colouring, there are distinct differences between this and the Newton Comics edition. In particular, look at the male figure on the right hand side near the fire hydrant and above Mr Fantastic's speech balloon. The original cover clearly looks like a Jack Kirby figure - even if the pencil work is too small to identify it, the posture is pure Kirby. However, the figure in the Newton Comics edition is completely different. In fact his shoe intrudes into the speech balloon!

Now, I'd love to claim this as an exclusive Australian edition variant, but I can't. The same modified cover is reprinted in my Marvel Masterworks Vol. 2, and a quick check of covers on the GCD tells me the modified cover was published as early as 1966 on nothing less than The Fantastic Four Golden Book and Record Set. It appears the modified cover has become the standard in reprints of The Fantastic Four #1. I've checked over a dozen cover scans from various US and International editions and they all have the modified version.

I'm sure there's a story behind this that Kirby experts have addressed before. I'm no Kirby expert, but I'm interested as to how this came about, so if there's a good article online or in The Jack Kirby Collector or some other reputable source about this, I'd be grateful to be pointed in the right direction.

Update 21/11/2018: Marvel published a facsimile edition of The Fantastic Four #1 in 2018 with the original cover. (A shame about the bar code and the new cover price.)

Update 13/12/18: Here's a photo I took of the advertisement for The Fantastic Four #1 as it appeared in the Sunday Observer 15 June 1975:

It appears conclusive that this issue was indeed published 14 June 1975.

The following two advertisements appeared in the Sunday Observer in successive weeks, 22 June 1975 and 29 June 1975 respectively:

Given they advertise The Fantastic Four #1 as being currently on sale until at least the end of June 1975, this does at least confirm my assertion above The Fantastic Four #2 was published in July 1975, meaning this series was not published on a fortnightly schedule as other Newton books were at this stage, although it would be shortly.

Update 15/5/2019: Here's a good rundown on the alternate covers by someone more expert and eagle-eyed than moi - there are more differences than I initially noticed.