So I actually agree that the effects of a late intake closing can offset high compression, but the issue can become that the parts are no longer matching for intended use and potentially adds a harder hitting compression problem as VE climbs. The 351C 4V is more fussy on both of these than our FEs because of lopsided port volumes and flow, combined with short stroke
I am not a 351C guy, but a 260-ish cfm intake with a 160-ish exhaust will want some split and on the street, a human sized primary pipe. The bigger or later the intake lobe, the the lazier a big port 351 will be. Additionally, although custom cams can widen the LSA to keep from too much overlap making that worse, especially when you add split, IMHO it won't offset the benefit from the early cam timing pulling on the port.
The second thing, overlap effectively allows the negative exhaust pulse to fill the cylinder more, as that engine becomes efficient at higher RPM, that onset will come faster and steeper, GREAT if the fuel is there, but not so good if it isn't
So I pick RPM range with the head and induction system I choose, cam for that, make sure the quench is tight, and for the street try to avoid domes (EDIT: although Brent pointed out that a closed chamber C doesn't need a dome at that compression), then pick compression for the fuel being used in that purpose. Brent can give you some nuance on successful combos as he has done more 351Cs than I have, but here's a little backwards math for 11:1
11:1 compression, and assuming a pump gas engine, and power brakes
You'd need somewhere around 300 adv intake, 310 exhaust on 106 ICL, at that point, a 114 ICL would barely get you power brakes, but without them would sound pretty healthy but be flat on the bottom with modern cams that's a real big cam. If you retarded it to 112 ICL, which is way old school and I wouldn't recommend it, you could likely run 286/296 and tighten things up to 110, but it would still be very soft on the bottom, this time from low vacuum. FWIW, that was what Ford did a lot. Late ICL, wide LSA. J-code 302s, CJs, both around 114 LSA and ICL, not the greatest combo compared to today
Now switch that to 10:1, you could be in the 276/288 adv range, have less overlap at 111 for clean operation and high vac down low (or go tight for a little more pulling on the port because you have room with overlap) but you can run at an ICL of around 106
So it may sound like I am jamming at the concept of adding cam, not really, but on a big ported, smaller engine, it gets you into odd places quick, especially on the street.
I'd dig deeper on gearing, vehicle weight, and intended use, then intake and header plan, then pick a cam, then go for unobstructed flame path and tight quench at whatever the compression range needs to for the fuel you need . I'd bet 9.5-10:1 is pretty close for the street pump gas
Remember, 10:1 vs 11:1, when matching fuel and use is a big difference, but, if you are closing the valve so late to get there, mechanically you are taking away the benefit at your working RPM. Drag racing, different function, different answer but you would need the fuel to do it too as it exceeds 100% VE, rapidly
