454/th400/np203 1970 k10 swb fleet

[BIGRAGU]

Hello guys,
I have recently purchased a 1970 Chevy SWB Fleetside. It has a 350 smallblock,TH350, and somebody has swapped in an NP208 out of an 80's Blazer. My plan is to drop in a 454 RAT and a TH400 and get rid of that ugly np208 and find a 203 for it like I think it would have came with. Has anyone out here done this combo in a pickup like this before? I am wondering if there are any unforseen problems that I am going to run into. I understand that I will need to get the right output shaft for the th400, for 4x4, and the correct adapter plate to go in between the th400 and the np203. I am also assuming that I will have to have some work done on the driveshafts. If anyone out there has any thoughts I would appreciate them. Thanks, Chris
P.S. If there is anyone within a couple of hundred miles of Brainerd MN that have any of these components for sale let me know.