I have seen the Toyota unit and someone I know is using them for a kit car series - tidy unit.A few people have gone astra pump.
My 2c is of your going through the effort to remove the engine driven hydraulic pump, do it properly and remove all the hydraulics and go for a Yaris or Barina direct electric assist column. Allows you to change the feel of the steering on a trimpot.
To add onto this, merc pump is on the left and astra pump is on the right. Bit of a size comparison for those interestedI have seen the Toyota unit and someone I know is using them for a kit car series - tidy unit.
A few of the boys now are using a Merc pump that is smaller than the Astra and available cheap new.