Yes you can, the pressure readings will be the same but the temperature scales are different. Also r12 uses 1/4 flare fittings and r134 uses 1/2 acme threads on the hoses. Unless it's a really good gauge set or you get hoses, adapters, etc for cheap or free then you can probably buy a new set...
Currently in the middle of doing my second set of intake manifold gaskets on my Wife's suburban with the 5.7 vortec. These gaskets are suppose to fix the common problem with the vortec, but so was the last set. Have also replaced the fuel injection unit with the updated one. GM loves to use...
Probably looking for something like this? http://www.ebay.com/itm/MARPAC-MARINE-3-WAY-BOAT-FUEL-VALVE-BRASS-3-8-FNPT-NMMA-APPROVED-7-6948-NEW-/291096008715
I have had one on for about eight years. They use Monte carlo calipers and 1/2 ton chevy rotors that have had the center hole enlarged. I think the only problem I had was some wrong length bolts. They don't have dust shields either but no problems otherwise. I thought it was a lot easier than...
Here you go, you can right click on the picture and use search google to find the image. https://forum.ih8mud.com/40-55-series-tech/788503-2f-affordable-fuel-injection.html