David,
The best site around has been proven again, you got great advice and sources for parts to make your job easier. The cooler should allow
oil to reach about 220 degrees as soon as possible because it needs to reach this temp to out-gas properly and is also the temp
oil is most effective (short answer). You need a T-stat or bypass valving to reach this temp in your system. Without this function
oil will take much longer to reach temp.
Cooler design or tube diameter should not restrict oil flow or it will cause a pressure drop through cooler. The hose size and length is also a consideration and should not restrict flow when t-stat is wide open. Engine builder will help with oil temps in terms of min/max and the viscosity that is best for your engine. As 210 220 is the min a good max temp would be around 240 to 260. I am sure others can help here with there min to max desired temps but go to the site of the oil you like and see the charts of (temp VS. viscosity VS performance).
Controlling this temp goes hand in hand with coolant temps. If coolant is out of control then oil temp will also be hard to keep in range.
Use good hose and fittings with protection from rubbing. Avoid strain on anything with engine movement if not on solid mounts.