That would also be a nice option, seen the fajs before, but bought the vw speedshop ones because the fajs were not big enough in my opinion
but I saw that they also sell bigger ones now.
As for using the dells as tb's that should be a possibility. A friend of my has 48 ida's as tb's. I dont know if it is needed to block the fuel/idle circuit, but maybe nice to machine the venturi for 40mm, because you don't need it anymore.
Regarding the ecu, I use Megasquirt 2 (extra, sequential ignition) for years now. I know there are a lot of other brands on the market, but don't have any experience with them.
Mark