That isn't a bracket I'm familiar with, and does appear to place the PS pump lower down than the usual setup, so swapping to the factory bracket setup should sort things out. This is the standard lower bracket, this one is from an '83:
Not pictured is a cast iron plate that goes between the block and that bracket, I think I have one here but will need to check and confirm, and the brackets that attach the PS pump to the top of that bracket, which I know I do have.
As you can see, the bracket relies on the AC compressor to stiffen the bracket, without the compressor fitted it's likely that the bracket will flex when the PS belt is tensioned.
If you want, I can cut the lower bracket down and weld on an angled brace in place of the compressor for extra cost.
Send me a PM if interested to discuss prices etc.
