Here is a 3 plate hydroboost kit mount I am selling that fits the Jeep TJ to a late (long rod) Astro hydroboost. It comes with a third plate to replace the Astro angled mount you can remove using a crowfoot wrench. You source your own 5/8" to 1/2" bushing for the rod end so it fits your pedal.
This pic was taken using a GM truck HB that had the brake rod threaded for an adjustable end but I can make them the exact length to fit the late Astro HB:
With this mount welded up you can simply unbolt the HB from the mount on your firewall to invert it if you want more valve cover clearance. I can build similar mounts for many applications so just ask if you want to source your own HB and weld your own mount to save some $.
These are $62 + shipping, in kit form for you to weld.
Interested? email me at sterlingworth16 at yahoo dot com
For comparison you can see here how the hydroboost replacement plates I make are lower profile than the early, flat Astro van mounting plate:
This is the cheapest crowfoot wrench I've been able to find for removing and re-installing the large nut on the back of the hydroboost. It's a little over $12 at Amazon.com:
Here's the CJ/YJ 3 plate hydroboost kit mount, same price:
The Mopar ('68 Roadrunner, etc.) 3 plate hydroboost kit mount: ....yes, I do other early Mopar also.
IH Scout II 3 plate hydroboost kit mount:
'67-'72 Chevy C10 3 plate hydroboost kit mount: