I have single line external oiling on 2 different cars and never have any problems w/ either one. Heard of people losing prime, but I've never had that problem in 15 years.
Only real issue I've seen is you need a deep sump pan for the external pickup. Can hang a lil low on the street. I use the 440source low profile aluminum pan on my hemi...works great and has good ground clearance.

My opinion for the OP...I'd use the 4.25" stroke w/ 2.2 rods, internal p/u so you can use a shallow pan if you want, and a solid roller. If you have good rockers, you don't need to lash the valves often at all. I check mine twice a year...I say check b/c they rarely need any adjusting.