This is certainly one in the category of investigating the local rules to see what's allowed, before you commit yourself.
Looking at a hydraulic handbrake myself at the moment for the FHC Sprint, will probably go for two small/separate callipers for the hand brake.
Which of course means converting to rear discs.
I do have a fairly simple rear disc set-up at the moment (from S&S)
which does the job (including handbrake turns) admirable with a cable operated handbrake, but there's room for improvement.
And I like the challenge of building it [;)]
You can do it with one calliper per side but you'll need a one way valve in the brake pipe for obvious reasons.
And that's another part that can go wrong ...
And welcome, ... mmm drifting with a TR7 [:D]
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<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="3"><font color="red">My full Weblog</font id="red"></font id="size3"></b></u>[/url]</b></i></center>