[Grumpy old man]

You can use a small battery charger to test seat function BUT there are many things to consider just hook the + lead to the red or orange wire and ground lead to the seat track

1 )many older caddy /buick seats had "plastic" transmissions to move the seats via a flexible cable to the actuators they break very easy and you can't buy parts for them

2) seat width many seats are just too wide and you won't be able to close the doors

3) seat height car seats just aren't high enough using stock seat tracks

4) power most power seats run on an 30 amp fuse and heavier gauge wire

5) physical size of the seat may have you sitting on top of the steering wheel

There are more than a few aftermarket truck seat companies out there and when you consider the amount of your time to retro fit old seats and old ripped upholstery (WHICH IS EXPENSIVE TO REPLACE) when you can buy new and correct fitting seats the cost really isn't that unreasonable ! better yet take your stock seat down to your local auto upholstery shop and let them give you a price for what you need !