[Bob Kontak]

Good job on the youtube video. Belt is definitely too slack. 1/2" max movement is the general rule. Get a new one and read up on how to mess with the shims and such to replace and tighten. It a bit of a PITA with a new belt to get the pulley-half close enough to the fan to get the nut on. With two peeps one can keep pressure on the pulley while the other gets the nut on.

God bless your Dad, especially if he helped you get into that car.

Be forewarned, there will be little annoyances that you will need to address over the next few years unless the previous owner was an absolute anal-retentive maintenance freak. Not too expensive as the problems will be the routine 911 version (dome lights, AC condensor relays, steering column bushings, yadda yadda). Just roll with it and do the stuff right. You are in the right place. Welcome.