Dear Dominic;
There's a Company in Texas that has "truckload" of 848 heads cheap, but I can't recall who etc. Patrick's may know.
Any 261 head is okay. The 848 is popular (only) because of the smaller chamber & 'instant' (bolt on) compression increase.
A later 235 head will work too. You just need to drill the 'steam holes' for use on a 261" engine. The early (pre 54) may oil the rocker assembly differently, so check that first.
Not to worry here.
