I decided I wanted a 20 degree tilt on the radiators to give the room I needed at the top of the compartment for the hoses later on. There wasn't much in the way of nearby structures to fasten the lower radiator mounts to, but interestingly enough the frame horns at the front of my new cradle were at 20 degrees. That made it a no-brainer to decide where the structural support would come from.
Next, I needed to find a suitable isolator between the radiator and the steel mounts to keep the fan noises from migrating to the chassis. I also needed to be certain that whatever mounting system I used, I'd be able to remove the radiators for servicing in the future. Ultimately, I resorted to reusing the stock Fiero rubber isolators... with a twist:
I took a piece of square steel tubing and with a bunch of cuts with my angle grinder...
...I made little cradles for the rubber isolators to sit in:
Then I welded the little cradles to outriggers made of 3/4" steel tubing :
And then welded a mounting tab at the end of the steel tube, so the whole thing looked like this:
Finally, I drilled and tapped two holes in the side of the engine cradle and one on the bottom side to attach the new radiator mount to the frame, like this, giving an automatic 20 degrees of tilt:
For the upper mount, I only needed something simple to stabilize the top of the radiator. The ducting from the door scoops will also play a role in stabilizing the radiators at the correct angle. As with the bottom mounts, I needed to find a rubber isolator for noise and vibration control. I happened to stumble across a couple of large circular rubber grommets whose inside diameter fit the post welded to the top of the radiator perfectly. Using some small diameter exhaust tubing on the outside diameter of the grommet allowed me to locate the top mount with a couple steel rods to the upper frame rail.
I have a neat little bender that installs in my vice for just this sort of thing. I used some wire to mock up the lengths and angles needed for two steel rods that would be welded to the exhaust tube, and bent them up:
Then I needed flat ends on the rods where they would meet up with the frame rail, so I heated them cherry red with my propane torch and hammered the ends flat:
Once all the parts were ready, I mocked them up, tacked them together, and then welded them. Here's the result:
For servicing, I plan to pull the radiators out from underneath the car, so this upper mount could be permanently installed. Here you can see the little aluminum post welded to the top of the radiator that needs to be centered in the rubber mount:
I held the upper mount to the upper frame rail with a couple large clamps, then slipped the rubber isolator in place:
Here's the overall picture: