When we converted my early non-progressivve power steering MA70 to a 1jz from a jza-70 front cut we connected the prog power steering as follows:
On MA70 there is a yellow 10 pin plug behind the glovebox which connects to all the instruments etc in the dash. A pink wire on this plug is the speed pulse from the speedo. We plumbed/tapped this wire (no cutting off plugs!) into the connector for the power steering computer from the jza-70. The jza-70 speed pulse wire is also pink, but if you want the relevant jza-70 and ma70 connector diagrams let me know your fax number and I'll try to send it to you (it's hand drawn). As far as I know the progressive power steering is now working. (We used the jza-70 front crossmember/suspension too). And it operates the power steering solenoid at 65 km's to change hydraulic pressure to the steering box.