Richard,
A picture of your firewall forward would speak a thousand words..
Look beyond airflow and oil coolers, and check other engine related items. This is what I found when I had a similar problem as you:
Read about the entire thing HERE (although the baffle/diffusers are all old in that post)
Is this a parallel
valve engine or an angle valve engine? Typically the angle valve engines produce higher oil temps because of the oil being sprayed on the bottom of the pistons drawing out more heat.
Check your timing.. With my engine, oil temp can be regulated linearly with mag timing. The more advance, the more oil temp.
I'm cooling 400 cubic inches, CHT and Oil, with less than 20 square inches of inlet area.
Tom