Here's how I narrowed them down:
1. Make sure all weapons and armor have 3 slots (refer to previous posts on how to do this).
2. Buy a new matching set of armor from the shop - in my case I bought a full Liberator set.
3. Do a text "Search All" for "invalid" or even better via Hex using the slot addresses from the prev post - this will bring up everything in your inventory which has no slots or partial slots (Liberator comes with 1 slot default).
4. Go to the results and check the decrypted text for parts codes (Liberator legs = AS_Legs_201). You only need one since the rest of the parts seem to follow the same numeric logic (i.e. AS_Head_201, AS_Body_201, AS_Arm_R_201 and AS_Arm_L_201).
5. Manually replace these with the part codes you want (You might have duplicates so it might not be a good idea to do a replace all).
Proof:
You can rinse repeat this method to get anything you want. Now I just need to work out the part IDs for Muramasa set.