Originally Posted by jroode32
...the gauges go to 800PSI on the high side gauge and 500PSI on the low side gauge...
The gauges you ordered will probably be just fine, but just for reference, the rule of thumb with analog gauges is that you want the 'range of interest' to be at half-scale.
I have noticed that when I need tools, I seldom find really great used or on-sale tools. When I don't need the tools or already have them, the great bargains are everywhere... so you might keep your eye peeled for a used R-22 gauge set. I would say $10 is a pretty good price.
BTW, I don't know if you read the whole 'manefesto' thread, but there is a section in there on the need to purge the inside of the copper tubes you are brazing, because tiny black flakes will form in the presence of oxygen. These black flakes can plug a cap tube or TXV orifice. The pros use dry nitrogen for this purpose... CO2 will work too, but it will have moisture in it which has no business inside a HVAC system. Some suicidal experimenters who are bent on their own destruction have used R-290 for a purge gas. Obviously, I would never recommend such a practice.