Can you buy the opposite end of a ball joint (the tapered whole)? I need to start making some suspension bits and would be much easier if they are available off the shelf

Never seen them... Would be a piece of wee to make some though. Isn't it just a tapered hole!?

You can buy morse taper sockets from engineering tool suppliers, but these are ver high precision, and I would suggest it will be cheaper to go to an engineering firm and have them make some for you.
Regards
Hugh

I've got some....transit bj fitting

You can buy ford bolt on steering arms from Burton and Rallydesign and compbrake

just search e-bay for "ford capri steering arms"