PM replied.
Long story short, was going to put these on my R32 GTR but found out that the head needed rebuilding so due to the extra costs involved, I'm going to fix the head and leave everything as is.
Will be leaving the engine side of things as is for a while but later down the track I'm planning on doing a single turbo RB30 or 2.8 stroker so there is no point having the parts doing nothing.
Thanks