Heresy placement question.

[DLStryker]

I sit 8 feet from my Heresys.  What would be a general rule of thumb how far apart I should separate the speakers.  How many degrees tilt in?  By the way, the speakers are pretty much in the center of the room.   The back wall is 13 feet behind the back of the speakers.  I have no other options in speaker placement other than adjusting the separation between the two.

[wuzzzer]

Equilateral triangle, speakers should be toed in aimed at you.

[KT88]

10 hours ago, DLStryker said:

I sit 8 feet from my Heresys.  What would be a general rule of thumb how far apart I should separate the speakers.  How many degrees tilt in?  By the way, the speakers are pretty much in the center of the room.   The back wall is 13 feet behind the back of the speakers.  I have no other options in speaker placement other than adjusting the separation between the two.

 

In your case, I would think that you would find it well out experimentally. You don't have a direct rear wall, which the Hereseys actually need for bass reproduction, but you do have the subs. So I assume that you are primarily concerned with the stage, the spatiality and a balanced, room-filling sound - room-filling at least from your listening position.
Spontaneously I had also thought that the Hereseys are a bit too close together in your drawing, maybe you actually start with an equilateral triangle where the listening distance remains the same and the speakers are further apart. That would be my starting point. From there I would try to see if it sounds too far apart or if it's just right. 
The way I see it: Mono recordings should still come clearly from the centre and not sound too wide and bloated. On the other hand, it shouldn't sound too compressed to the centre if it's a stereo recording.
I like to use two very different types of recordings to get it "right". Of course, you have to bear in mind that everyone has their individual preferences within a certain framework. That's why my post can only be taken as a kind of general suggestion.
The first type of recordings are typical 1960s Bluenote or e.g. Riverside Jazz recordings...often e.g. a saxophone from the left channel and a trumpet from the right channel. Maybe a piano and or drums from the centre or a third horn player. All instruments, no matter where they are placed, should have the same energy and the soloist from the centre should not sound broader or softer. E.g. Art Blakey "Moanin" with Lee Morgan and Benny Golson.
Once I have solved this task, I take a second recording where the spatiality and the overall body of the orchestra are important. Good classical recordings, e.g. from Deutsche Grammophon or others such as Decca London or Columbia, are suitable for this. something like a piano concerto or violin concerto. But also recordings like Dark side of the moon...
With both types of recordings, I can optimise the angle of the speakers to suit my taste. This is where my experience speaks for itself: it can be different for every speaker! I don't know the Heresey, but I would bet that I wouldn't aim them exactly at my face. Many speakers sound best when I can see something of the inner side walls at my listening position. For example, the small BBC LS3/5a which I love very much are only angled about 7 degrees, that's not just my impression but general knowledge over the decades. The larger BBC LS3/6 are angled more so that I can only see two fingers of the inner walls.
My Underground Jubilees stand in the corners of the room and are angled at 45 degrees like a Klipschorn but less works also.. My old 1977 LaScalas are angled in such a way that I can see a good hand's width of the inside wall, so they are not angled in too much. I would assume that it might be similar with the Heresey, at least as a starting point. But that's exactly what you'll be trying out. In the end, your listening taste will decide, but perhaps I could contribute something to the start of your experiments. I wish you lots of fun and success.