Do the VTL MB450's require matched tubes??

Factory matched quads from one of the two main vendors (New Sensor / Antique Electronics) is all that's required.

New Sensor represents Sovtek, Electro-Harmonix, Tung Sol (reissue) and JJ.
Antique is distributor for SED Wing C and also sells JJ, EI, Groove Tubes, Valve Art, Ruby Tubes, Golden Dragon, and some NOS.

Based on my listening tests and (likely) what your VTL came with from the factory, I suggest SED Wing C as replacement tubes. They are somewhat hard to come by right now, I had 100 on order since four months ago and only received 50 so far. This means dealers who sell the SED may be asking a premium, so shop around.

they do not need to be match, you are going to do that when you bias them, svletana 6550s sound best, bias at about 27ma

I don't believe matching is an issue, since the tubes are individually biased. I have the Wing C in mine.