#1 - you dont need to buy a fuel pressure gauge - you measure the fuel pressure at the valve by the FPR. its the same valve as the air valve for you tires, so all you need to do it press a tire pressure gauge to it while it running.
#2 - if your saying your truck has NO spring in the FPR. then there is no need to do any BB shim mod because (A) typically that mod is done to help boost pressure caused by a weak spring, and you need a new one anyway (B) if you need to buy a FPR spring anyway, then either get the cali spec spring from the dealer, ($45), or the upgraded spring off ebay ($10), and you will have both replaced the spring and still bmped up your pressure another 10- 20 psi over what it should have been
6.0 & 7.3 DIESEL FUEL PRESSURE REGULATOR SPRING | eBay
Ford Powerstroke Fuel Pressure Regulator Spring 7.3 FPR | eBay
and in case nobody else told you - its also a good idea to remove the water in fuel sensor in the rear of the fuel bowl,
and replace it with a brass plug. if you change the fuel filter normally, you dont need that sensor, and its not the oring in the sensor that leaks, its the sensor itself. this is also another VERY common area for fuel leaks. also - there is a weap hole under the fuel pump. when the pump goes bad fuel will begin to leak from that hole as well. lastly - the cali spec spring on my truck boosted my fuel pressure from 60 to 80 psi..
"California" Fuel Pressure Regulator (contains spring, valve spool & new brass plug)
From Tousley Ford Parts online: MSRP $36.67; Online Price $24.20
i keep coming back and adding to this... it was a good idea to toss the heater. its more trouble than its worth.. mine cost me $500 to have my pcm reflashed when it shorted. you probably wont NEED to replace it even it you head back to Montana. instead of having high pressure fuel lines, our fuel runs through the head on each side. so once the truck starts to get warm, that basically acts like a fuel heater.