I will be very interested to hear how you get on with these. I made myself something very similar and they cause a lot of clunking from the suspension, particularly when negotiating a change in level like a kerb.
I believe the Steve Heath items are no longer available. I have seen some upgraded items at TVR-Parts but just wondered if other options exist including DIY.
I have the Steve Heath ones although had to replace all the rise joints due to them seizing. Replaced with stainless steel ones and booted them for added protection. Been fine since.