I had another look at that 6-string bass bridge I found on eBay, and the string-to-string spacing on it is 16mm, which should work perfect with the original bridgeplate, so I'm going to buy one of these next week, and just use the saddles, intonation-screws, and springs from it:
https://www.ebay.com.au/itm/38393169...2Cchnl%3Dmkcid
Sourcing a set of new strings might be a pain though, cause I just checked Stewmac, and although they do sell a set of 6 DAddario XL 6-string bass strings, they are currently out of stock on it.
https://www.stewmac.com/strings-and-...g-bass-strings