If you have the main oil gallery drilled for an external filter, consider the plumbing. If you use a dual exhaust setup the plumbing becomes more of a headache. Whatever you do, be sure to use 1/2" ID hose and protect it from manifold heat; braided line and AN fittings is best. Make sheet-metal heat shields if necessary. Also consider that the filters available by application for Mopar products (a common application for aftermarket remote filter mounts) are rather coarse, something on the order of 30 microns, so they will flow enough oil. There is a Wix number 51515, also under NAPA with a similar number, it is much finer and is physically larger so even so there's not much pressure drop across the filter. Hot Rod Lincoln says there are low-micron hydraulic system oil filters available but I haven't looked. I found a Franz toilet paper filter and added that as a bypass filter. Oil stays pretty clean.
I also installed a spin-on coolant filter with sacrificial zinc in it to prolong the coolant change period. Dodge application, I think but suitable for systems up to 4 gallons. That way I don't have gallons of spent coolant to dispose of as hazardous waste. My filter nount came off a 220 Cummins stationary engine but you can use the same remote mount as for the oil filter.Put a shut of valve on both sides so you can take the filter element off without losing coolant. I had the radiator cap off the other day and shined a flashlight down it. Clean as a whistle and has not been to the radiator shop in decades. My incentive for the filter was the amount of hard black sludge in the back corner of the block by the drain cock. I had to use compressed air to blow a channel so it would drain. Same story on my 235. The filter should catch that before it has a chance to settle out.
These engines came from the factory with exhaust-valve rotators. They greatly extend the live of valves in heavy service. I'd be surprised it your engine doesn't have them. If not, find some if you're going to put it to truck duty. Yes to bronze valve guides and also positive stem seals. The machine shop can cut the guides to take these. Don't get the exhaust stem-to-guide too tight. They will hang open if they get too hot, scare you with the noise and maybe bend a pushrod. Happened to me near Salton Sea (-200ft. elevation) on a cold, clear morning, i.e. dense air, lean mixture. I'd tuned for 3,000 ft. No pushrod trouble though.
