'54 Strats didn't come in blue... All Strat bodies from '54-'56 were Ash, after '56 all were Alder, except for those with blonde finishes which continued to use Ash. Caps were usually ceramic disk type .050 ones, those can be hard to find, a .047 cap isn't going sound any different really.
If you're trying to re-create a '54 vintage sound, use an Ash body and an all maple neck. There are lots of "vintage" Strat pickup sets available, but it's hard to beat the Fender Custom Shop Fat 50's, especially for the price.