So I've always been interested in vans (So much room for...anything)

I recently came across a 70'-89' Chevy 1 ton Cargo Van
I helped my neighbor move it within her yard
Wants to sell it to me for 700 bucks, has new wheels/tires.

The only thing that's wrong with it is the engine has a knock in it, but I figured for that price I could just toss a new engine in for around 1200 bucks

So I basically have two questions;
1) It kinda looks like a Candy-Van (rape van) and she even mentioned that the previous owner got pulled over to make sure he wasn't hauling immigrants from Mexico, is there a simple/cost effective way to make it look less conspicuous?

and 2) What kind of engine should I toss in it? (if I cant easily fix the knock of course)

Thanks again guys, you have some awesome looking rides!