Update: Ok so fitment without welding didn't work out. The injector port locations on the Honda flange need to be welded and then cut in half to clear the Mazda injectors. Also the angle the manifold sits off the head wasn't exactly ideal with the plenum very close to the chassis with some of the vacuum ports hitting. The TPS also hits on the chassis so the throttle body would need to be turned 90 degrees which would require an adapter as the bold spacings aren't equal.
Instead I've decided to cut off the flange and weld on a new one. Simpler and easier to get the required alignment.
I ran the manifold through my table saw to cut off the flange at an angle for the runners. Also I drew up the flange in CAD and had it waterjet cut out of 12mm ally. Once welded, I'll reface this down to around 10mm. Also made up 6 triangular braces for strengthening.
Above photos show it's fitment in the engine bay. There is a good inch clearance around the brake lines and biasing valve. This isn't much of an issue for your LHD cars, but for the RHD models fitting the Skunk2/Blox pro manifolds won't work without moving the brake lines and biasing valve. I'm still sorting out placement of the fuel lines which are a bit awkward with the stock fuel rail, probably easier with an aftermarket rail.
The throttle body angles off at a great angle, missing all the pop-up light mechanism. I'm planning on building an air ram and filter box in the space left from running the Honda half width radiator. It will see half the front mouth's air pushed into a flat filter and up into the air intake. Nice cold air with a smidgen of added pressure.
Angle is pretty much ideal now for flow into the head. The 70mm throttle body looks serious with the added bonus of the Mazda throttle cable fitting straight in. The cable mount also happens to bolt on to the plenum with bracket that came with the manifold without any modifications... Couldn't have worked out any better.
Triangular bracing underneath. There has been no cleanup on the welds. I need to machine the welds flat around the mounting holes. I only put 6 braces on so you can't see them from above... it also means it's easier to access the two end nuts.
I have to finish off fitment, fuel lines etc and it will be off to dyno next week. I'll be also tuning for E85 as well so I should get some solid numbers on the improvement over stock manifold as well as running E85. Will be interesting to see some real figures.
Overall I'm very happy with the fitment. It looks like it belongs on the motor and hopefully will see some decent gains for the effort.