Thanks for the advice everyone.
I'll verify which head is mounted before I order anything.
KiwiGF would it make the most sense to order the carb that corresponds with the type of cylinder head? (I.e. cast iron vs alloy)
Hi ADP91, a simple answer to that question is “yes” but ideally one would look at the bigger question of what bike you wish to end up with. Many of these bikes are not “standard” (eg as they left the factory) now, for one reason or another.
So, if your frame originally belonged to an iron head A7, some would go to great lengths to fit an iron head A7 engine to it, similarly for a frame originally fitted with a super rocket engine.
Conversely many (probably most) bikes are a mixture of original parts from different models, and of course “pattern” or recently manufactured parts.
You have (at least) the drive side crankcase from a super rocket, most likely you have the timing side as well, but nothing else about the engine is certain!
The uk bsa club has very good info on engine and frame numbers see:
https://www.bsaownersclub.co.uk/machine_id.phpAs an example, the “correct” Amal carb for my iron head 1956 golden flash is a type 376 1 1/16” monobloc, later golden flashes had a type 389 1 1/8” monobloc, and the (alloy head) super rocket may have had changes in carb spec over the years as well (I'm no expert). Certainly some super rockets had the 389, but I have a feeling when the golden flash got upgraded to the bigger carb, the super rocket got a bigger carb as well.
Many people fit the correct bore size amal concentric carb if they are not worried about originality, its cheaper and arguably a better design.
I hope that helps rather than confuses
