Never or seen or heard of such a thing, but it doesn't look too difficult to modify an existing sump.
Do Alpines have alloy sumps? If so it might be easier to start with the steel sump from a Super Minx (long time since I've looked under a Super Minx but I'm fairly sure they have a steel sump).
No. The finned alloy sump was introduced for certain Arrow range cars.
Modifying a standard early series Alpine sump (the type with the dipstick tube on the side) was my final option but it does involve quite a bit of work.