Hello there!!

[Slider in Wa]

New guy to your board. Retired, have a few knowledge based questions. I have a 1948 Chev COE, currently running a 455 olds/t400. The body is setting on a 1988 1 ton dually frame. I want to change the engine back to Chevrolet, and put it back in the engine compartment. It currently sits behind the cab. Mid frame. I need to know if a 250 inline six will bolt up to a five speed tranny? I have been told the 90`s Chev 5 speeds (Truck) will make a stong tranny, however i do not know if it wiil bolt up?
Is there an overdrive automatic that will bolt up and last. I will be using the truck for hauling and pulling a trailer.
What are my options?
I am open to suggestions. Mostly doing the learning phase right now. I do have a 4 bolt main 350 , that i can rebuild, but have an intrest in putting a six back in it.
Hea , thanks for listening!!!! Everyone have a wonderfull day today!
Slider in Wa.