Clarification needed...W-series parts swapping!

[Dan-TSS]

Can non W series heads be put on a W series block, if you use the non w series headgaskets?

I thoroughly read the Service Bulletin, but where I get stuck and confused is the next section that follows concerning vehicles orignally equipped with the later w-series engine. It states that no later parts can be interchanged(well, that's atleast how I am interpretting it).

*Any solid proof before I spend some money?Please.
Dan 8)

[Gritt]

yes, w-series heads can be installed on non-w blocks, using non-w gaskets. i have run motors that way. no problems