The V8 Owners Forum -

Lumiweld is a kind of brazing for alloy, you do it with a blow torch. Haven't done it for years but when I did it either worked or it didnt, its all about how clean you can get it. You can also mig alloy though you need pure argon. Best done with a spooler as the aluminium wire is a bit soft to be pushed through the hose reliably but for small jobs a normal type mig can be used.

"Badger - there isn't room to go adjacent to the normal injectors, I did look at that, and it's completely inaccessible under there. The fuel rail and injectors completely fill the void under the inlet pipes. You are also supposed to get the pipe between injector nozzle and injector valve body as short as poss...... "

Chris, I can assure you without a shadow of doubt that there is room - because I've done more conversions on Thor engines than I care to even consider! It is indeed tight, but it can be done easily.
The critical length for the hoses is 12", it can be done fitting them where I said, but you have to route 2 pipes each side rearwards then up over the upper half and 2 forwards through the gap between the side plenum(s) and the front chamber then back over the upper half, with the 2 injector banks mounted running fore and aft right in the middle, picking up on the upper plenum bolts with a home-manufactured bracket for them, with the gas nozzles facing outwards on each side.
It has also been done mounting the injectors as explained above, and the jets going straight into the manifold at 90 degrees to airflow just above where you've made your dirty big holes. Both will work just fine.