Calling all corner carvers!
Yeah, that's going to be tough. The thing about the US Cartool inner fender braces is that they're just an "L" shape, they really use the inner fender as the wall to complete the "box". Without that side they'll lose a lot of strength.
The only way I see that working at all would be to weld them to the upper shock support, which gets boxed as part of that kit, and the cowl. The shock mount reinforcement shouldn't burn through to the inner fender if you leave off the inner weld, and the cowl side would burn through on the inside of the firewall (which needs to be bare with all the padding and carpet removed). So it would be solid at both ends. If you welded tabs to the inner fender support you could then bolt it up against the inner fender in between the shock mount and the cowl. I think the result doing it that way would still be better than having nothing there, but it wouldn't be nearly as strong as if it was welded down both sides of the brace to the inner fender. Not having the shock mount welded to the inner fender at that end would hurt it, although you might be able to reinforce the shock mount a little more on the sides and and to the frame rails to make that part stiffer without hurting the engine bay paint.
Another option would be to use a tubular support there. Welded solid at both ends with landing plates and then tubular in between. Remember XV Motorsports? They had a tubular brace like that. Turns out they have returned, one of their former people started XV Engineering. Now, I would be skeptical still. But they've been around for a few years now. Anyway, this is their product, which I think might work better for you since it won't be welded the whole length of the inner fender, just at the cowl and shock upright which should keep burn through off of the visible part of the inner fender.
XV INNER FENDER BRACE A Body
This is a picture of a similar brace that was made by Dillinger Chassis, it's a little different with the landing plates and would work even better. So you could have a set made up, or use the XV pieces and alter the landing plates to attach just to the upper shock mount.
Here's the thread on those. Dillinger isn't in business anymore, but there's more pictures if you wanted to have a set made.
Custom Inner Fender Braces 67-76
Yeah, that's going to be tough. The thing about the US Cartool inner fender braces is that they're just an "L" shape, they really use the inner fender as the wall to complete the "box". Without that side they'll lose a lot of strength.
The only way I see that working at all would be to weld them to the upper shock support, which gets boxed as part of that kit, and the cowl. The shock mount reinforcement shouldn't burn through to the inner fender if you leave off the inner weld, and the cowl side would burn through on the inside of the firewall (which needs to be bare with all the padding and carpet removed). So it would be solid at both ends. If you welded tabs to the inner fender support you could then bolt it up against the inner fender in between the shock mount and the cowl. I think the result doing it that way would still be better than having nothing there, but it wouldn't be nearly as strong as if it was welded down both sides of the brace to the inner fender. Not having the shock mount welded to the inner fender at that end would hurt it, although you might be able to reinforce the shock mount a little more on the sides and and to the frame rails to make that part stiffer without hurting the engine bay paint.
Another option would be to use a tubular support there. Welded solid at both ends with landing plates and then tubular in between. Remember XV Motorsports? They had a tubular brace like that. Turns out they have returned, one of their former people started XV Engineering. Now, I would be skeptical still. But they've been around for a few years now. Anyway, this is their product, which I think might work better for you since it won't be welded the whole length of the inner fender, just at the cowl and shock upright which should keep burn through off of the visible part of the inner fender.
XV INNER FENDER BRACE A Body
This is a picture of a similar brace that was made by Dillinger Chassis, it's a little different with the landing plates and would work even better. So you could have a set made up, or use the XV pieces and alter the landing plates to attach just to the upper shock mount.
Here's the thread on those. Dillinger isn't in business anymore, but there's more pictures if you wanted to have a set made.
Custom Inner Fender Braces 67-76