Hi Chris,
Alclad is a semi-transparent metallizer (the surface beneath the coating controls the effect as it remains
visible 'through' the Alclad) rather than a 'paint' per se, and as such isn't really worth the extra cost if one
just wants to paint a 'silver' aircraft.
However, if you want to practice with the product, it does apply differently than regular lacquers or enamels,
then I'd go for the dull aluminum over a smooth grey primer. Use thin coats, and as it is semi-transparent
don't expect it to build like a heavy opaque silver enamel.
Cheers