Fantastic Four #147 (Pt 21) Dr. Doom, Rama-Tut, Ben and Reed

Fantastic Four #147 (1974) Rich Buckler

Fantastic Four Annual #2 (1964) Jack Kirby

Fantastic Four #147 (Pt 20) Sub-Mariner and Super-Skrull

Fantastic Four #147 (1974) Rich Buckler

Fantastic Four Annual #3 (1965) Jack Kirby

Fantastic Four #143 (Pt 4) Darkoth, Reed Richards and the Gang

Fantastic Four #143 (1974) Rich Buckler

Fantastic Four #71 (1968) Jack Kirby

Fantastic Four #143 (Pt 3) Dr. Doom's Terrible Triumph

Fantastic Four #143 (1974) Rich Buckler/Frank Giacoia

Fantastic Four #64 (1967) Jack Kirby/Joe Sinnott

And sure enough,  #143's Reed and Medusa are patterned after #64's Reed and Sue! 

Fantastic Four #143

Fantastic Four #64

Fun fact: Marvel's Greatest Comics #47 reprinted FF #64 with the Kirby cover slightly tweaked by John Romita Sr. and was on sale about a month prior to FF#143. 

Honorable mention: Fantastic Four #14's cover 😉

Fantastic Four #150 (Pt 14) At Last!

The last panel in 1974's Fantastic Four #150...

Fantastic Four #150 (1974) Rich Buckler

...and the last panel in 1969's Fantastic Four #83. 

Fantastic Four #83 (1969) Jack Kirby

Fantastic Four #150 (Pt 13) Crystal and Quicksilver's Wedding

 Wedding of Crystal and Quicksilver--Fantastic Four #150 (1974) Rich Buckler

Fantastic Four #99 (1970) Jack Kirby

Fantastic Four #150 (Pt 12) Black Bolt's Back

Fantastic Four #150 (1974) Rich Buckler

Fantastic Four #59 (1967) Jack Kirby

Fantastic Four #150 (Pt 11) Medusa Descending

1974: Fantastic Four #150 Rich Buckler

1969: Fantastic Four #83 Jack Kirby

Fantastic Four #150 (Pt 10) Human Torch Unlucky in Love

From Page 27 of Fantastic Four #153 (1974) 

Breaking it down:

Fantastic Four #150 (1974) Buckler

Fantastic Four #45 (1965) Kirby

Fantastic Four #150

Fantastic Four #45 again

Fantastic Four #150 (Pt 9) Avengers Assemble! Inhumans Too!

Fantastic Four 150 (1974) Buckler

Fantastic Four 83 (1969) Kirby

Fantastic Four #150 (Pt 8) The Mighty Thor

Fantastic Four #150 (1974) Rich Buckler

Thor #143 (1967) Jack Kirby

Fantastic Four #150 (Pt 7) Ben and Johnny Have a Fit

Fantastic Four #150 (1974) Rich Buckler

Fantastic Four #99 (1970) Jack Kirby

The sequences:

Fantastic Four #150

Fantastic Four #99

Fantastic Four #150 (Pt 6) Ben Grimm, Alicia Masters and Sue Richards

Fantastic Four #150 (1974) Buckler                                  Fantastic Four #99 ( 1970) Kirby

Fantastic Four #150 (Pt 5) Franklin and Reed Richards

Fantastic Four #150 (1974) Rich Buckler

Fantastic Four #89 (1969) Jack Kirby

Fantastic Four #150 (Pt 4) Ultron and Ben Grimm

Fantastic Four #150 (1974) Rich Buckler

I'm sure there must be plenty of prototypes for the Ultron pose (such as in Avengers #57) as it's a fairly standard "attacking antagonist" pose, but here's the image that immediately came to mind:

Fantastic Four #71 (1968) Jack Kirby

Also, here's the Ben figure:

Fantastic Four #150

Fantastic Four #44 (1965) Kirby

Fantastic Four #150 (Pt 3) Ultron and Dragon Man Disperse the Crowds

Fantastic Four #150 (1974) Rich Buckler

Fantastic Four #44 (1965) Jack Kirby

Fantastic Four #150 (Pt 2) Ultron-7: He'll Rule the World!

Fantastic Four #150 (1974) Rich Buckler

Fantastic Four #81 (1968) Jack Kirby

We've seen this image of the Wizard before, remember? ;)

Fantastic Four #150 (Pt 1) Group Shot

Fantastic Four #150 (1974) Rich Buckler

Fantastic Four #44 (1965) Jack Kirby

Also, Medusa in the #150 panel is reminiscent of Medusa in this panel from 1969's FF #82. We'll see this Medusa image used again in another issue. 

Fantastic Four #82 (1969) Kirby

Fantastic Four #143 (Pt 2) Sue Richards--Drama Queen

                                           

Top: Fantastic Four #143 (1974) Rich Buckler/Frank Giacoia

Bottom: Fantastic Four #109 (1971) John Buscema/Joe Sinnott

Lichtenstein would have loved Sue  😉

         

1964

Fantastic Four #143 (Pt 1) Dr. Doom and Medusa

Fantastic Four #143 (1974) Rich Buckler

Fantastic Four #84 (1969) Jack Kirby

Note: based on the preceding panels and the dialogue here, I think this is a pic of Johnny, but the colorist thought it was Reed.