67 Riviera wheels

[Guest Black beauty]

Could someone tell me which wheelsize will <span style="font-weight: bold">definitely</span> fit the drumbrakes on my '67?

I know that they have a 5on5 pattern (15''), but I don't know which backspace will work with the big drums in the back (in the front I have discbrakes )...

I think the original wheels have 15x6 offset 0, so nothing over 3'' of backspace should fit in there , right?

The problem is that I 'm thinking about putting 15x8 in the front and 15x10 in the back, but I can't find aftermarketwheels in that sizes with a backspace under 3 1/2'' and I don't want to cut the cooling fins...

Any experiences...?

Thank you for your help...