I built a mild 351 Lightning shortblock with 1.9 170cc Ebrock heads and Explorer top port matched to a GT40-351 lower. It was going in a heavy car with an AOD so was afraid of over camming. My first foray into small block Fords. So, I went with a stock HO cam (after I converted to mass air, not expensive, bought an aftermarket adapter harness and used mass air meter).
Had it dyno'd just to make sure of air fuel ratio. Had pretty good torque for such a mild motor but the hp curve didn't rise much after just a little ways off idle. WAY under cammed! Even with 1.72 rockers.
Without changing anything else, I put in a TF Stg 1 and it was a world of difference. Even with the small heads. TF was only about $100, way cheap for a new roller. It's 218 intake @ 050 and I would have preferred something closer to 212 but can't beat it for the price. If I ever dug into it again I'd try advancing it 3 deg or so to stiffen up the under 2800 rpm torque just a hair.
The car as I mentioned was originally a SD car so had done some research on upgrading it before I ran across the 351 L motor. Here's some cam info from a couple guys that did a LOT of research and hands-on with SD 5.0's in Lincoln Mark VII's which weigh in at least 4,000 lbs.
Just FYI you can usually find the mass air conversion harnesses pretty cheap on eBay, I think I gave around $30+ for mine a few years ago. I found a used 5.0 mass air ecu for an auto, worked fine with larger injectors and matching calibrated air meter (again, everything used) with no tuning or chips.
And here's some info on intakes -
I can't say enuf about the street throttle response of mine. I don't know how easy it is to find GT40-351 lowers any more, from what I know Ford quit making them some time ago. The next best street intake I would believe would be an Ebrock Performer (or Performer RPM) upper on top of a 351 pickup lower. Any of the high buck aftermarket ones are just too soft on low and mid range torque and don't beat the Explorer / Cobra type up until after 5k rpm, and how often do you see that kind of rpm?
I found my heads lo miles used at a great price and are great for a mild 351. AND no piston interference even with 1.72 rockers for about .535 lift. It's worth shopping for good used even if you have to wait awhile. There are often some twist wedges available pretty reasonable which make a great street head for motors like ours. Also no piston interference problems.
A couple other minor things - don't go a hi volume oil pump, in the 351's stock ones are more than adequate in street rpm ranges and don't waste HP pumping more oil than needed and dont' wear out distributor gears.
OH, you'll have to get the Ford yellow stripe gear for roller cams and switch if you're working with a Lightning distrib. From my experience, even with a drill press, I'd never tackle that again. Take it to a good machine shop after you do the measurements to determine gear height on the shaft. You can do a search to find out how.