On the connectors, I used the parts from a turbo harness as I got it with the engine, NAPA might have pigtails for ya but I'm not sure, they do for a lot of things. Anything that connects up should be the same like injectors and such. One sensor you probably don't have on your truck is a MAP sensor, don't remember if they had them on the MAF engines (mine had a MAP sensor, not MAF, it was an '89 build sold as a '90 model year), the turbo engine uses a MAP sensor as a BARO sensor so you'll need one, just grab one from a junkyard if you can from a non MAF Ranger, they're mounted in the firewall just above the heater box and have a vacuum line going to it.
On the LA3 without an intercooler, the main physical difference that the LA3 cares about is the air temp sensor in the intake manifold, it doesn't care if there's an intercooler, it just takes the intake temperature into account for fueling. You can get it together with an LA3 and just get it going and modify things down the road to get an intercooler in the mix, my engine has been in for right at 5 years and I haven't gotten that far yet
The advantage of the roller cam over flat tappet is the roller cams last forever and don't wear out, current oil does not come with additives to help with flat tappet cams anymore, and like you found out there's less friction. The reason people use the Ranger roller cams is they have a similar grind to the turbo cams, and are apparently just a little better... with a turbo engine you want more low end power in the cam profile to help the engine along before the turbo kicks in, it'll add it's own air after that