Help with a 58 300GH Hydra Matic retrofit

[1project2many]

I have had two different versions of this trans. The 3/4 and 1 ton trucks have different gear ratios than the 1/2 ton pickups. As an experience. They're different from what we're used to today. The hydraulic coupling slips more when starting from a standstill and when driving, the shifts weren't as nice, and there's no park position. Also, they weigh as much as a second engine. If I wanted to go "all original" I wouldn't hesitate to use one but for the simple goal of installing an automatic to make the vehicle easier to drive I'd choose a 2004R transmission with lockup torque converter over the original Hydramatic. With either swap you'll need to make changes to crossmember, shift linkage, floor plate, and possibly exhaust but with the newer transmission you'll have less trouble obtaining parts from donor vehicles to modify and you'll find more aftermarket parts available if you need them. And, your local transmission guy won't hide under the table in the break room if you have to come in for repairs.