Header fitment rant, Doug's
Man that isolator looks massive.
A lot thicker than my stock biscuits
As for the engine brackets, I'm pretty sure you cannot swap them side for side, but there are several bracket sets to chose from, over the years. Your brackets look kindof right to me, but like the guys say something looks odd.
My biscuits are squeezed flat between the brackets and the mounts; tight to both no airgaps.
I know you know,the trans mount positions the engine fore and aft, then the brackets, laterally. IDK if you have a problem, but I would remove both mounts and measure the offsets from bracket hole to mount hole and see if the stud offsets on the biscuits match. If the trans mount is off, it will give you fits.
My TTIs required two different thickness shims, so I could move the entire engine over to the passenger side, and level it there; and I lowered the rear mount.
I used stock old-style biscuits and a Schumacher torque strap. I had to clearance a couple of tubes for the T-bars, and another for the pitman stud. This on a 68 Barracuda with a 70Duster 340 K-member. The rear X-member was from a 73Dart; spool mount, with a poly insulator.
Hang in there; you'll get it figured out.