Alternative to MS-5?

Need some advice here. Currently working on the Tamiya MacLaren MP4/13. I need to find an alternative to Tamiya Spray MS-5 (Metallic Grey). The hobby stores I went to do not carry the MS range of sprays. The sales guy recommended the Light GunMetal spray but it's a little too light for the MacLaren.

I don't have an airbrush so I may have to brush paint it metallic grey.

:(

I used Gunze Sangyo Mr Surfacer 1000 as a base coat. Will the enamel paint affect it in any way?

NOOOOOOOOOOO
for the love of models, don't brush paint!