Vacuum gauge read the same as when it was left 16+ hours earlier, so system has no leaks.
Installed 1 can of 134a refrigerant, then started the engine. With engine running at 1050-1100 rpm and A/C on high, added another 1.5 cans for 2.5 cans or 2 lbs total of 134a. HP side indicated 175 psi with 81 deg. OAT, with LP side indicating 75 psi. System seems to be cooling well. Shut down engine & A/C, disconnected gauges and capped service ports. Will re-install the cowl tomorrow after engine has cooled down.