BSP are usually tapered threads and are used on many fittings....
If the threads are the same, but without the taper, You may still be able to fit them.
I'm not sure whether female brass fittings used on engines are tapered ?
Maybe only the male part is tapered, so it just screws in until it doesn't leak, helped of course with pipe sealant or teflon tape.
Many shops sell brass fittings at reasonable prices...
Bearing/seal shops.... engineers supplies etc..
Most speed shops sell brass and aluminium and stainless steel fittings at Very expensive prices....
best of Luck
Lee
http://community.webshots.com/user/vw68autobug