If you've got the money, buy the painless performance wiring harness. If not, the harness out of an 87-91 van is much easier to work with than the truck harness. You will need a speed sending unit for the fuel injection to work correctly.
A tube mount is just that, it is a tube bent with v8 mounts on it that is easy to put in your frame. Some people use a front horseshoe or U type mount.
You must support the bellhousing from the sides as the SM420 was not available with a tailhousing mount like the SM465 was. How do you plan to mount the bellhousing? Do you have something fabricated already? A circle track mount with two biscuits works nicely.
