Oz I think you are right. OP if you are sure there ain't no (good) number on it I'd still suggest askin what the parts house has to provide for a range of years of WWC apps for ~66 383's & other size engines in that range as needed. Yes it definitely would be better to soak it especially after all those years idle. Carb cleaner ain't stout like it used to be (EPA regs) but you can get a gallon & set the carb in a container & fill up the bowl & let it set so the fluid gets to all the innards & the cluster might fit in the carb bowl to make it even easier. I would not remove the jets