Howdy sikyne,
Good to see some other people taking on interesting/difficult challanges,
I hope all works out for you, don't give up.

First obstacle for the GA head is that all 10 headbolts do not line up, 8 do but two need to be modified to work.

As far as driving the twin cam head is concerned I have gone for a new duplex drive sprocket of the crank, (it's worth noting here that I am not using a A-series crank and therefore had to adapt a drive sprocket to a different nose on the crank, and then machine up a new crank pulley to suit, if it was an A-series crank it would have been so much easier, ah well!)

For the driven reduction sprocket I am going for a triplex sprocket, machining one set of teeth off and and replacing that set of teeth with a sprocket of the same number teeth as the original camdrive sprocket to retain correct timing, therefore, driven duplex drive off the crank and the original simplex drive for the cams.

On the driven side of the duplex timing chain I am making a Auslon (bearing grade plastic) chain guide and the tension side I am going for a spring tension arrangement similar to the original GA set up, the original oil pressure chain tensioner is retained on the head for constant cam timing.

I am using a 3 stage dry sump pump with the tank in the back of the car and a external water pump controled by the ECU.

The timing case cover is a bit of a challange but nothing too hard.

I will be running 50/48/45 EFI Hardware TB's on a manifold I bought from South Africa, extractors will be similar to 'LZ' ones.

Like I say this will eventually be the head on my big 1860cc bottom end, I hope to make an honest 200hp reliable motor.

Just out of interest, I will be adapting a BMW Getrag 262 CR 1:1 fifth gearbox behind it and a original Nismo Works H190 rearend built for a Works Stanza.

I have alot of work to do next year.