From what I have found is, its a Honda replica with OHC unlike its predecessors which were OHV setups. It does have a tiny internal pump producing around 4~5 psi to shift the oil when warmed up, I'm guessing its a impeller type running off the gearbox or another internal system.
It doesn't have a real oil filter in terms of a paper type, it has a strainer (mesh) filter in place. Some of the kits I've seen cap the return at the strainer and place an external oil filter of the same type and feed back in after the cooler but this is all on the OHV. My main concern on this engine being a OHC is whether the return goes to the rocker to splash the cams, its hard to judge without physically taking the engine out and apart. Usually there's a bolt somewhere for a return on the side of the engine but I've yet to spot one. As typically they use the same parts for the 125, 150, 200cc just the heads vary, but the OHC variation is their latest creation so no ones really tried much, I know the 200cc has variation has a oil cooler as stock but without many images or schematics I cannot tell where or how the manufacturer does it.
My idea was to pick up off the strainer, block return on strainer, supply oil cooler and the return part I'm struggling on...... Maybe feed to rocker or back into where you top up oil as that will be low pressure, but my concern is where the return goes encase it does keep another part of the system lubed. Maybe not block the return and just split the oil strainer two ways, if this is an option would oil pressure be significant.
Any more input is appreciated.