SMALL BLOCK ENGINE BRACKETS/MOTOR MOUNTS
Have you seen what people are asking for the OEM pieces lately.
189 isn't a bad deal with all the hardware.
Measure the upper ear spread (rear side to rear side) on both sides of your block, if the same width, you need the easily available 273-318 brackets. Drivers side more narrow, pony up for the 340-360 brackets.
I was taking 318 mounts, cutting them up and making them into a 340-360 compatible mount. Many on pretty stout SB's, no issues, knock on wood!