How about a 10Rp4 or is it an 10Sp4 - it's shorter than a 10 bp4 and it's aluminised. For that matter,a round CRT from an RCA camera viewfinder might fit the bill,too as it isn't a 10 inch tube- it has a smaller screen and shorter length. Also aluminised in the versions I've had. If I had a tube manual in front of me , I'd look it up for you.
I've seen them come up on Ebay, usually going without a single bid.
Most of the people selling them have no idea what they are supposed to be used in so the descriptions suffer.
Good Hunting !
Bob Hodge
