Seemed to have missed this one Alex. Looking great so far. The bulkhead would be zinc chromate, but it's also a lot further back than as on the kit, where the engine is part of it. Better to paint it black, then it doesn't look too artificial.
I had that problem with Humbrol Matt Coate when they changed from tin to jar too, even after stirring for ages. I now use Johnson's Klear/Future, and add Tamiya Flatt Base until it's right, either matt, semi-matt or whatever. If too much Flat Base is added, it'll dry with a white, chalky deposit, but you can test first, by brushing on to some scrap. Just add a bit more Klear to cure it. BTW, only add the Flat Base a small amount at a time, until you're happy with the result.
It will go on beautifully with a brush, and if applied evenly, will dry without brush marks. Have a go!