V8 Core Support ??

[Coupeguy2001]

There is a top spacer, which you have, and a lower splash pan,which you don't show.
There is an angle at the front of the top spacer to support the spacer, and a bracket in the middle to reinforce the whole mess (I have that somewhere) and it bolts onto the cross bar for the core support.
So, in all, you have to have 4 pieces.
1. top spacer,
2. bottom splash pan,
3. angle,
4. brace.
There are extra holes in your inner fender panels on all V8 models for the ends of the radiator core support on each side. Move your radiator core support back about 8 inches, and pick up the V8 set of holes. Then it will be clear.

Originally, GM made the V-8 kit to move the radiator back to the engine for the shorter engine, and in 1958, they sped things up on the assembly line by just adding the shroud for 58 and 59 on V8 models.