Awesome
Souns like I'm going to get some good mileage as I have the same set up sorta.
Using the 700R4 with a .70 overdrive and I have a 9" rear end. I don't know the exact gear ratio but I did spin it around and I did some looking up and I think it is one of the smallest gears they made. I think it is a 2.55. I only have 27" tires in the back so I bet that ratio will make up for the difference but I'm not sure what overdrive is in that 4500 tranny your dad has.
I plan on running an intercooler so hoping for a bit more efficiency out of the turbo. If I could get 40MPG and 200HP I would have a grin from one ear to the freaking other.
I'm going to start my thread here soon....week or two or three

. But please post up some of your dads pics and please tell me all you possible can. I would love to hear more about it. My truck is Yellow now (sorta) but is either going to be white or red. I haven't decided.
#1 Here are a couple pics of when I got it.
#2 After I blasted, boxed in, and painted the frame and got some new panels in over the rust.
#3 And now as it has the donor 6.2L that gave me a basically free rebuilt 700R4. I had nowhere to stick the 6.2L for now until it goes in the Land cruiser.