I have not seen very many angle valve jugs, let alone seen an angle valve engine alongside a parallel valve engine for comparison. Since Lycoming saw fit to add a lot of fins and
oil jets, they were obviously concerned about dissipating the waste heat from those extra 20HP
And apparently the fins work, since the cylinder head temps are maintained as well or better than on parallel valve engines, with less mass flow.
For the same power setting (absolute, not percent) does an angle valve engine require a larger oil cooler (more mass flow through cooler) than a parallel valve engine? If so, one could infer that it takes both fins and oil jets to keep things comfy. In other words, choice C on the list at the end of Dan's last post.