74 Gold Duster and tons of questions

thank you very much for your answer. just to doublecheck it:
in each case i have to rebuild the engines. if i find a 318 i can upgrade it to a 340 with a kit? or im better with buying a 340 then stroking a 318?
i need a lot of stuff like hedders, mounts and so on. i need one of those two transmissions you said. i'll look which rearend i have. then you can tell me if its allright?
for the shark tooth grill i need for shure a older hood, bumper and filler panel. i have to see if the 74 fenders fit.