The pressure switch is a hobbs adjustable which you can find on Ebay for $30-$50, the one I have was used for years on my Reliant. Just do a search for "hobbs pressure switch" and look for one with either three contacts or just "normally open" two contacts in the 35-60 psi range. The correct switch is black and gold with a hex on the end for adjustment. At NAPA the same switch sells for $85!
The relays are also from ebay "DC 12V H3Y-2 Delay Timer Time Relay 0-30 Second 12VDC & Base" or you could simply do a search for "12V time delay relay" The ones I found are the first referenced and only $7.50 shipped each.
The WOT cut out can be either mechanical off the throttle or vacuum, the vacuum one I used is part number "PSF-102 PRESSURE SENSOR" $12 shipped.
I'm going to be swapping to a switch off the throttle, they are typically $14 for a universal WOT switch from Summit or Jegs.
