Engine and transmission

[Bonzai]

Long time dreamer first time owner... Needing some advise as I am learning as I go. I just bought a 72 C10 heavy half and wanting to use it as my daily driver I'm over spending 40k for new trucks. I'm also going to buy a mid level 5th wheel and do some traveling
Soooooo being someone who is mechanicly incline enough to get me in trouble I'm looking for some wisdom to tell my better half on why this is the best idea I've ever had lmao.. And besides 40k more like 60k for a truck with all the bells and whistles to pull a camper.. I know pushing it with this truck and should own a 1 ton but damn I love this truck and thinking may pull it down to the frame.

I have a 350 that is running rough at low Rpm has a knock or tap rod or lifter? Seals leak nothing extreme couple drops on the ground. Oil level not dropping. Engine seems loud bearings?? Manifold?? Would not think its the original motor because of what appears to be a vette fuel injection looks like block been painted orange flaking to reveal more orange underneath it. Automatic 3 speed transmission which is wet also and spinning oil off u joint has spilt axel carrier bearing shot rear end is a greasy mess not sure what gears are slinging oil off that u joint to.

Guy I bought it from had it in storage for 3 years to rebuild it never got around to it so he's not much help. He bought it from a guy in Tennessee that used it to pull camper to Florida every winter. Been reading a lot on the forum and it seems 50/50 split rebuild to crate motor.. I'm leaning towards crate 350 from Jegs making it 260 hp for reasons I'm not sure and new transmission what kind no clue.. rear end gears?? What types of issues I'm going to run into installing.. Drive shaft etc.. Not sure how much truck frame can handle on weight and how much it can pull

So there's my long winded questions I'm sure I'll think of more.. And mayb I'm pipe dreaming and can't get away with this and push it into storarage when I'm ready to travel and tell the Mrs. I changed my mind on what truck I want to use lol