Re working the stock head as Steve shows is your best option from a economical stand point. It will still have decent compression, and if you dial in the squish gap to the rec
commended .8mm it will have higher than stock comp.. Probably in the 145 psi area.
Using the head Steve shows on the right will require a good deal of material removal from the jug or resurfacing the jug to use a teflon tape style gasket. I've herd the tef. tape gasket works well. You will still be left with to wide a squish area without opening up the dome. Too wide being relative as to what one is looking for. You have probably seen the earlier posted perf. results.
Of the heads below the left head with the fins that converge toward the plug is a 6cc head. It will bolt on with no compression loss over the slant plug head, and has a squish band close in width to what Steve produced at 7.5mm. The other two while having the narrower band are still like the flat head Steve shows in that there volume being 8cc will need the same work to maintain a good compression, i.e. decking jug or tef. tape gasket.
So since it's not that hot where you live the only draw back to the stock re worked head is constant re torquing.