I am moving along...
Swapping from swing axle to IRS requires a modification to the shock absorbers. The internals are 100% the same, there is only 1 difference: The sleeve in the lower rubber mount: On IRS, there are longer sleeves:
The brake hard lines had to be re-routed, too:
I used the brass fitting attachment points on the IRS brackets which are from a beetle chassis:
Shift rod connection also done - safety wire was added later - make sure you use the type 3 specific "hockey stick" in the gear box!
This is the current status: