Hi - I just came across this thread a few weeks back.Thanks.
The set neck was produced by Fender Japan in 1997 (ST-145RB) and was available for 3 years, so I believe there were produced several more than just a few.
But a few were built at Fender Custom Shop. Might be those you mean.
I haven’t really understood this signature model, as Blackmore never had, or used a set neck. He glued the necks to the bodies.
The ST-145RB was indeed scalloped but had a standard bolt-on neck. In excess of 500 of these were produced in Japan only from 1997 to 2001.
The ST-175RB was the 'set neck' version with a glued on neck. The join was finished with the vintage white paint to create a smooth seamless join. This guitar was again produced in Japan only from 1997 to 2001 and it is thought around 50 were made. The scalloping was light, similar to the ST-145.
A third set neck guitar was made in the USA Custom Shop. This Ritchie Blackmore Custom Artist Series was made between 2001 and 2005. Around 30 were made and there was an additional option to have the guitar Roland ready. The scalloping on the neck was more aggressive than the Japanese versions. These guitars had only 2 lace sensor pickups.