[Jittsl]

My spec Boxster (obviously trak car) used to have the stiff and vague shift issues when very hot. Cooler hooked in and out at the fill and drain holes has resolved the issue. My suggestion would be make it as easy as you can on yourself and just go with the existing holes and don't do anything more extravagant than the basic set up you described. For track/road car I think the nonereturn would be critical. You might also consider a faucet on the return line so that you can ensure no overfilling. If you do not I would run it every now and again because nonreturn valves often let oil slowly creep by.

When you are building your setup consider ways to make sure that as little oil as possible will want to return under gravity. For example most people mount the cooler with the in and out holes at the bottom. In my case, I mounted the cooler so the nozzles go upwards through the trunk floor and oil is sucked through by the pump. The consequence is that, when not used, the oil stays in the cooler rather than wanting to return to the tranny. Likewise the filter (before the cooler) and pump (after) can both be sloped so that the low end is at the cooler. In the end (in my case) the non return valve (mounted at about the level of the oil in the tranny on the line leading from the drain) only has to stop a small amount of oil contained in the pipe rising up to the filter and the rest simply remains where it is until the pump is run - that is except the oil that was in the return tube which I calculate as part of the standard oil requirements IE when it has drained back the oil is at the correct level or slightly high)

Hope this helps and makes sense, if not send me an email address by PM and I'll get some photos over to you.