For those wondering what has been happening with this project.
There's been a few issues since I last updated and I've had to do a few house jobs, which delayed progress.
More testing indicated that it was a bad air leak and not a fuel supply issue via the cut fuel rail causing the lean mixture, but I have since linked them together.
It turned out to be misaligned inlet manifold gaskets. When I had lowered the intake onto the valley, two rear cap screw heads on the vacuum chamber cover came in contact with the gasket overlap and consequently as it was lowered further they pulled the gaskets down at the rear ports. Stupid design.
But after fixing this the a/f ratio gauge still indicated an air leak. I eventually found porus pin holes in the welding on the front section of the cover box. I had decided to test fill the cover box with water and upon blasting air around its perimeter it turned into a friggin bubble bath. I took it back 3 times before it was finally made airtight. Sheeeeeeez, nothing I could do about others workmanship.
But again on startup the a/f gauge still showed signs of a very minor air leak at idle. Aaaaaaagh about now I was getting frustrated to say the least,

. A big problem was that none of the air leaks made tell tail noises so it was impossible to ascertain where they were and access was not ideal. But I traced this one to a rear injector housing base. Turned out that this section of the top main plate was not absolutely perfectly flat so when this injector housing was bolted to the plate it had tilted a few thou.
During all these shenanigans I did several test drives and even with the a/f ratio not being perfect the results are just friggin awesome,

so I definitely wanted to retain this injection setup.
But it would have to be super reliable for long trips and after a lot of thought I concluded that this current setup was prone to developing further air leaks due to the many bolt holes and gaskets so the only answer was to completely remake it to eliminate this possibility.
There was no point in thinking about it, so once again I've been burning the midnight oil,
This time I used alloy spacers so they could be fully welded to each housing and then welded to the top main plate as this would eliminate 32 bolts and 16 small gaskets. Also by using a thicker main plate its sides could be machined for an O ring seal to get rid of the former 12mm square bar edging and its 12 bolts.
I made 4 alloy spacers and precut them to match the bore of each injector housing but cut them just short of coming through the top. I then fitted 2 small locating pins in each so the welder guy couldn't screw up their location on the housings,

Thankfully. I've now found a young guy who is a gun alloy welder.
After they were welded to the housings I then positioned the top plate on the 4 housings and using the pre drilled centre holes as a marker drilled the main plate and bolted each injector housing to the plate so they could be welded in the exact position.
Fully welded and the top and bottom surfaces faced.
Again using the centre guide holes I then cut through the main plate and the remaining bit in the injector housing spacers. Also I made access to the inner base flange bolts via a common cover machined into the main plate rather than use the former brass plugs.
The top manifold is now a complete one piece alloy unit without any bolts or gaskets,

. The only holes are the main 8 plus 2 for the PCV and fuel pressure vacuum brass fittings. The three central access holes are blanked by a sealed cover and the main cover bolt holes are blind. The O ring groove is much better as it only takes seconds to feed a strip of O ring rope into the edging.
Initially, I wasn't too happy about doing it all again but it was a wise move as this setup will be infallible.
JD