Since no one has answered...
The Girling brakes suck, cost more, and suck. No reason to go with these unless you must have original, sucky brakes. (did I mention they suck?)
Original suspention? well leaf spring is original to most small block cars, coil to big block cars. Some like the leaf better, most don't.
Billit suspension parts drop your un-sprung weight (coil suspension), steel tubing is however original.
The power booster would be tough since Kirkham uses the original pedal box design under the floor and I can't see a brake booster getting fitted. (at least not a vacuum one)
Unless you must have it original, go with the Kirkham setup.