4L80E with Th400 driveshaft and fuse box questions

[Nodnarb76]

The parts are piling up In my house now, motor and trans should be here soon from LSX4U.
Couple questions for the experienced ls swappers.

My swap will be an LQ4 4L80E into an 87 R20 2WD Suburban originally equipped with a 454 and Th400.

1. Using the dirty dingo slider mounts will I have to shorten or lengthen my driveshaft? Sounds like my Th400 yoke will work with the 4L80E, just wondering what might need to be done?

2. Probably a dumb question. Once I remove the stock TBI harness, I should still have power my fuse box right under the dash correct?

Thanks in advance.