@edsnova hmm, they're 0.8"/ 20mm OD (I've not checked ID, but googling similar shows an ID of 0.5"/13mm). But they're definitely feeding oil to the cooler.. Which then begs the question, what kind of efficacy will there be if the oil has to go 8 feet forward to the cooler, then 8 feet back to the engine. One could argue that it would give the oil longer to cool down, but the flipside is that the oil may struggle to come back from the cooler if it's thicker? I'm guessing it would depend on what temp the thermostat opens up?
One other question I was going to ask, given this is a 22+ year old conversion so I've no real history of why certain build decisions were made.. As this is a 1904cc build with some kind of hot cam (not sure what yet), does it benefit from both an additional slimline sump for greater capacity AND a full flow oil filter & cooler? I'm betting the answer is "given oil does double duty in terms of lubrication and cooling, then any help in looking after that oil is a good thing". But I'm happy to be corrected if wrong.