I used this as part of a complete front strut change, including a built in roller bearing at the top.
And I used "standard" 2¼" competition springs ...
Worked pretty well but at (high [:I]) speed and bad road surfaces they eventually hadn't enough suspension travel for my liking so I went a bit further ...
As for the clearance at the wheels, that depends completely on what wheels and tyres you're using.
Bear in mind that with wider tyres space is rather tight ...
But you can use the standard or aftermarket TR7 springs and upper spring seat together with the adjustable lower sping seat.
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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="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>