...... I recently purchased wheel adapters to convert but don’t think it will be sufficient. .....

You'll need to describe these adapters in detail, and then what it is about them that you don't think will be sufficient.

 

I bought them from wheel adapters USA , they are 1.25 in thickness and are a 5x5 to 5x4.75 conversion.

 

If you've bought the spacers and already have them, then it should be a simple matter to install them with those wheels to check whether there's any objectionable bind or rub, along with whatever your desired spread/tuck.

I chose 1.3 in thickness with 5x5 to [EDIT] 5x120 for my Fleetwood. As mentioned, whatever you consider to be 'sufficient' is a matter of gauging the car's original wheel offset compared to the new wheels. Here's my prior study:

Spacer/Adapter For CTS

My new fitment questions are not getting much traction in the Wheels section, so hopefully more experience here with this sort of stuff. To start with I've rounded up a set of '10-'14 CTS 18"x 8 1/2" and Conti Extreme Contact DWS06: In trying to clear the skirt skirt tabs without going...

www.impalassforum.com

 

What is the offset of your wheels?

 

I do not know exactly, but I believe it is low

 

You need to know that specifically, because it determines the thickness of your spacer/adapter.

 

Just be aware that 120mm is not 4.75. It's like 25thousandths smaller. Seems lot of camaro guys done similar. Suggest you tighten the lugs evenly in small increments to try to keep them centered.

 

Damm fine point, and my post edited for clarity.