The only person I have experience with, who also happens to be the guy who restored my Pantera, is Don Byars of Full Throttle Panteras in Lake Elsinore ( http://fullthrottlepanteras.com/ . I believe he's installed this electric power steering system: http://www.ezpowersteering.nl/..._Tomaso_Pantera.html .
SACC's system should be a bit easier (and cheaper) for him to install because there's no VSS to deal with.
A bigger alternator is a good idea but if yours is working fine, I'd probably leave it. Don's a better person to ask than I am. If you want to do it yourself, Pantera Electronics has a kit: https://www.pantera-electronic...m/12sialternator.htm