Slant six to small block 340-360 engine won't fit.

pass side slant to v8 conversion is truck mount bracket IIRC. Or really close in dimension

https://www.engine-swaps.com/products/67-72-a-body-s6-to-273-318-or-340-360-conversion-kit
Unless he put a V8 K frame in the car, that looks like the correct engine bracket for the slanty K