Hey Russ.
I did exactly as you suggest: the Fuse Panel was first (and I drove her for about 500 km's)and then the ISC.
I have yet to do the HMC because I do not know if the previous owner replaced the stock plastic gear in the headlight motor with the brass gear. This is a required mod prior to installation of the HMC.
Let me know if you have any questions relative to either mod. I plan to add some pix to my blog to show off the ATO panel and the ISC (in more detail). I was/am a total novice, but was able to pull off this work.
EA
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.