Comets and Maverick are the same,but the site I was looking at had a different part# for a 71-73 Comet v8 with manual and floor shift. I called to ask why and was told that 71-73 should not have been listed with that part# and that they would fix it.
I just dont understand why some on the forum have had a hard time on the install of 6901's. I've been tinkering with Mavericks for well over 25 years ( 3 mavs over that time period ) , the first Mav was a 302 w/ c-4 trans the other 2 Mav's were 5.0 w/ T-5's trans. All three had 6901's, never a problem on the fit, never. Now thats not to say that they will drop right in over a matter of 5 mins cause they wont , you will need a floor jack, 4 good jack stands ( lift and screw jack works much better, if available ) 1 --> 4 x 4, 2 --> 2 x 4's, concrete pad and an hour or two.
I have 6901s on the Comet, had to remove the column shifter linkage to get them in and raise the engine a bit, but they fit.
Headers I have Flow Tech # FLT 12100 Headers on my '74. Easy install. I had to raise the motor an inch or so to get the drivers side in.
I've had to do the same with my 71 Maverick with the column shift linkage, but I'm curious how you raised the engine a bit, as that's what I now need to do.