How much space btw driver & back baffle?

I just bought a 15 inch scoop from Mans1000[on speakerplans] and it measures 7 inches from edge of speaker cutout to back chamber baffle.

So only the Fane Collosus 15B will fit, the depth of it is 6.32 inch.

But will that leave enough space btw the pole piece vent and the back chamber board??? I guess if I add wadding to the back chamber the pole piece vent will be blocked.

Or will Eminence Kappa Pro 15 with depth of 6.05 inch be better???

Otherwise I might make the chamber bigger?? but that makes chamber closer to the adjacent chamber behind it. So not sure on that one.

So would any of those above would be fine as long as pole piece vent is not tight against the back baffle??
So whats the closest the driver can be to the back chamber board???

Also I won't be able to add wadding behind the driver if the air gap is tight, but can I add it on the sides and top of chamber instead???

I could get the JBL 2226H for £115 in a box, take it out the box and use that. Depth on that is only 5.5 inch Cept i've heard bad things about JBL so dunno on that.

Also the box has got no handles so gonna add some large metal bar handles to it.

And the venue me gonna be using it in is on the 2nd floor.
So where do I fit the large metal bar handles???? on the sides of cab or top and bottom of cab[being careful where the flare is].