I'm not sure about the pump, as I've never had a/c on an old car. Compression tester is pretty cheap, maybe 30 bucks? Good to have in the toolbox to quickly help diagnose piston ring/ valve issues . Don't forget about a rad overflow jug to help keep your garage floor clean. I've used a old windshield washer jug ziptied to the rad support with the overflow hose drilled thru the cap, ( until I found a correct jug).
