Customs tariff codes for sending used parts to the US?

I'm hoping someone can help here. I'm sending a cylinder head to a member in the US from Denmark, and I need to fill out a proforma invoice for customs. As part of this,
I need a customs tariif code for used motorbike parts, old.

Hopefully this will avoid problems with the new aluminium tariffs (!!) , excessive customs charges etc. ?

I am aware of the problems involved when using UPS or FexEX, so this is going via PostNord as a normal parcel (with insurance though.

Should be able to find it online, as they are generally available to.

I _think_ its 87141000 - anybody have any qualified opinions here?
/Steve.