The trick about chromium intensification is that the chromium bleach builds up density while it bleaches, the development step afterwards recreates silver density while (hopefully) not removing chromium density. If you bleach with ferricyanide instead, then redevelop, you will not gain much.
Which brings up Ralph Lambrecht's point: Ferricyanide is mostly harmless, but Dichromate is quite toxic and overall nasty. Yet Fotospeed is apparently able to sell it without repercussions. I have read a lot about photographers being harassed by British/US police (or rent-a-cops) for taking pictures, but never for possession or use of photo chemistry.