Tips needed on buying and installing '71 Duster lower door hindge.

My 71 Duster's lower door hindge needs to be replaced (broken spring and door sags a small amount). My initial question is: how hard it is to install the new hindge in a manner that has the door properly aligned? It looks like I'll need to remove some inside trim (driver's side) to remove a couple of the bolts from behind the hindge. At first glance - it also looks like I might need to unbolt the door from the upper and lower hindges in order to gain access to one of the bolts that attaches the hindge to the car.

Any/all advice would be appreciated.

Also, I've found a full set of hindges online but would prefer to buy one hindge vs a set. Any good sources for a single hindge at a reasonable price?

tx,
Ken