Vintage Air Not Cooling Properly

[ItDoRun]

Need some help with my VA Gen IV system in my 68 Camaro. Been fighting a cooling issue now for about 5 years (off and on) and I'm about ready to pull the entire system out and go another route. I've charged and re-charged the system probably 5 different times per VA's instructions. I've changed compressors to the SD7 Sanden. The issue I'm having is the vent temps will only get down to around 58-60F. AND as you start driving the car and everything normalizes, the vent temp increases to about 64F. The last attempt at troubleshooting, we hooked the gauges up and i rev'd the engine to 2000rpm and held it there. Low side was reading 5psi and high side was at 225psi. This was with the 24oz. of recommended freon. We added a few ounces and the pressures increased to 8-9 low side and 300 on the high side. Car is dripping water so there's nothing plugged or frozen up.

Called VA and they want me to "start from scratch" and asked me to drain the compressor oil and change the dryer. Also asked me to add back in 8 oz to the compressor but Sanden calls for 5oz so i'm already doubting the tech and because I've done this several times, I know it'll yield the same results.

Sooooo, all that said to see if someone on here with AC experience has any clue as to where to target my next troubleshooting efforts this weekend when I recharge the system.

Bad expansion valve? Blend door issue?

I've talked to several folks in my area with similar issues who have just given up on VA but it's too hot in South Louisiana to not have AC.