1967 Dart Drivetrain swap.

In addition to what you already have, you'll need conversion motor mounts, from Schumacher or TransDapt, a four-speed floor hump (part of the transmission tunnel needs to be cut away and a factory "hump" needs to be welded in. The revised floor will need new four speed specific carpeting also), the clutch linkage rods, adjusters and pivots.
That rear end is a no-go. Besides being waay too wide for an A body, much less the tiny confines of a Dart wheel well, '98 vans had a huge bolt circle- 5x5.5" if I recall correctly. And it ain't an 8 3/4, either. 8 3/4 stopped production in '72-'73, depending on car line. What you have is most likely a 8.25 or 9.25 depending on the van's weight rating.
As for the wiring, the slant uses basically the same wiring as a V8, year by year. Some of the wire lengths may need to be tweeked. The real differences are in different years, and whether you're going to be using electronic ignition, newer alternator and electronic voltage regulator, etc. That is where the differences will be.