My radiator and engine are just like yours. It's one of the more common variants.
Throttle spindles get bent by clumsy engine withdrawal/insertion and heavy booted drivers.
I have designed and built a small batch for Matt Foster but I think they are all allocated. I'll be talking to him at the AEC rally this weekend with a view to making more. Watch this space. (not literally, there's nothing in it).
When your pigeon is back on duty, ask him/her kindly to increase the welding current a bit. It will make the poop a lot runnier and might fuse your parts better.