I got 2 cents I can toss in here.

The ZF5 is a great option, can be pricey and some work. With the 400 I've read there are some clutch issues but others have done it. Gary Lewis did a good thread on putting one behind a 351M in a 81 https://www.ford-trucks.com/forums/1...-zf5-swap.html. As others have explained there are 3 cases, small gas, big gas, and diesel. You need big gas, this is good they are by far the most common. There are also 3 ratio packages that can be swapped between cases if you want to get into it. One is a "close ratio" with a more useable(not granny) 1st for regular use, IIRC this was used in some diesels. And of course they are overdrive transmissions.

However there is a relatively easy and cheap way to get what you wanted in your original post. To the best of my knowledge the NP435 was only made in one ratio package. But prior to the NP435 Ford used Borg Warner trannies that IIRC are all but a direct swap for the NP435. Specifically mostly T18s, T18s are part of a family/evolution of trannies the T98, T18, T18A, T19, etc. Close ratio versions of both the T18 and T19 were made that have the kind of gear package your after. As far as I know they were never put in Fords but in Jeeps, Internationals, etc. But those trannies are relatively universal. I am of course pulling all of this out of a head that hasn't looked at this stuff specifically in a while so do a lot research if this is a path that interests you don't just take my word for it.

There are a lot of options all depending on how deep you want to get into it, money, etc.