[v8volvo]

You're 100% sure you have all the air out of the system? If the core flows even just a little bit, I suspect it should provide heat?

Changing the core is a big job (ask ngoma) and unfortunately I don't think those of us in the US will have access to any information about how the non-AC dash and heater box are assembled, since all 700 series in the US came with AC. I don't think my greenbooks even show the non-AC system though I can confirm later on.

Maybe worth asking folks on one of the larger gasser Volvo forums? Turbobricks has a few members from Europe that participate and maybe they would have better info about your setup. Or see if the Euro versions of the Haynes manuals show something?