At the moment I am running a 350 Holley, after finding out the availability of a triple 45DCOE Weber set up, I am very interested to go that way.

The 4.1 is stock other than the 350 and extractors, but it performs quite well.

Initially I would like to fit the Weber set up on the motor as is, eventually doing up another engine with suitable mods to go with the Webers.

I'm interested to know if anyone has run a similar set up and what way you went with head, cam etc.

I wish to stay with the Cast X-flow head, I used to run Webers on street/race cars and liked their ease of tuning.

My thoughts are Port & Polish Head, Cam, Balance and any desired mods (ie; timing gears etc) recommended, still primarily a street car though.

Transmission is a C4 Auto, what would need doing with it, the diff is a standard LSD as fitted to the GXL six originally (not a 9inch, I suspect a 2.92 ratio? or thereabouts).

I would really consider changing to the alloy head, the ports are even unlike the cast head and the point of the we here is even distribution across the board, a ported alloy head has a lot more potential in it and gives you different chamber options for comp change if needed for a bigger cam.
As for the C4 a well built stock c4 will be fine, the diff I would change to a 4 pinion 28 spline centre just for reliability.