I was looking at coilovers and saw a coilover shock at QA1 for a 67 camaro.
I also saw a spring listed for that shock that was made like a beehive 2.5 in.
at the shock and 3.5 id at top which is the same id for a H body pocket.
The spring and shock specs are listed below at summit links.
Take a look and see what you think. They list other springs also as well
as a single and double adjustable shock (GS401 and GD401).
I think the lower control arm would need a little more bracing for the shock.
QA1 Precision Products GE401 - QA1 Economy Pro Coil Systems
QA1 Precision Products 11GSP250 - QA1 Coil Springs