Vincent sv 237 Tube Question

I just purchased this amp and was curious about the tubes. It appears as if it came with two GE 6bq7a's and one 12ax7. Not being too familiar with the 6bq7 tube I did some research on it which turned up very litttle info. I did find an article on i-fidelity however which featured an article with Frank Blohbaum the amps designer.

In the article Frank states that typically the 237 shipped with 6n1p tubes but a special series of the 237 came with the 6bq7a's. My question is are the 6bq7's and the 6n1p's interchangeable? I called Kevin @ upscale since he sells Vincent products and he seemed mystified as to why Vincent would choose the 6bq7a and did not think the 6n1p would work.

Im curious to know if anyone could clarify this for me, hopefully any Vincent owners will chime in. Thanks guys
I think the only replacement for those is a CV5365. But that's a rare tube as well. Do you need to buy new tubes?
Not looking to buy new tubes just curious.