Does the silver finish hold up in marine environment?  Seems Dichromate adds another 120 bucks on the price or so.

You can always treat it after the fact with either Alodine #1001 (clear) or #1201 (normal green/gold color).  You apply it full strength if brushed on, or dilute 3:1 if dipping.  I get it from Aircraft Spruce, around $35.00/gallon.  A gallon of the #1201 will do 20-30 Holley carbs to like new condition.

Cheers, Mark