few ? about 75 Dodge Dart Sport

[Jonn]

I am 49, worked on and owned a lot of these old cars in the past, however its been years and you forget so much of what will swap, my son n law just got a 75 Dart Sport 2 dr. with a 3 speed tranny and a slant six engine, The model that has a body like a Duster..

my, "refresh my mind" questions are:

will a small block bolt up to his bell (ie: 318/340/360)? and any specific parts need used ?

also would he need a rear gear ratio change going to a V8 ?

and, if he would go to a sb V8 and a auto tranny, would the 3 speed drive shaft work? tranny mounts? etc

also looking around sites for new interior parts, like carpet/headliner/seats and seems most listings stop at 74 model, his is a 75, any idea why?

Guy he got the car from has a lot of parts he can get, just trying to figure out which way he wants to go, thanks anyone for any input