Grind, grind, grind.
Were I to do it again, I'd have a machinist flycut the bore into the thing after scribing where the relief needs to be, and then go back with cartridge rolls and blend everything out afterwards.
The Turbo and late model TB's are similar, they have the heater on the body. The Weber is NOT what MSA sells. They sell TWM. I know, I just bought one, and had previously installed a Weber on another car 15 years ago. The Weber uses your old linkage over, the TWM unit MSA sells does not, it comes with it's own self-contained, slightly weak return spring. I had to rig another return spring on it to get positive return (one like the OEM body had).
I think they put that in there as TWM does not specifically state it is for the Turbo model. Check a Turbo OE body with a N/A body and if they are the same, then the aftermarket should work. That's what I'm betting on, I will be using either the TWM or the 240ZX body on my turbo car, but that project is two months off, and I haven't dug out the OE Bodies to really positively verify "yes" or "no" for myself...