air injectors work the other way round to an amal and bleed valve, they bleed off air, air injectors bleed air in.
if you are going to keep the T3/4 turbo, then they are a bit OTT as the wastegate will be fully SHUT anyway as the revs pick up, so it won't offer any better boost control over an amal valve.
The reason why they are needed on big turbo car's is that at high revs the wastegate is opened to bleed off air and the injectors allow this to be super accurately done within 0.5 psi, whereas the amal valve does not have this degree of accuracy.

That said, accuracy is the key factor, you either have it or you don't.
Don't forget £350 for injectors, another £200 to have them mapped in

HTH
Rick

air injectors work the other way round to an amal and bleed valve! they bleed off air,, air to air bleeds in