I would think the mildly ported TF270's would be pretty close in flow numbers (=/- 10 cfm in the .300-.700 lift range) to my Chapman stage 6's that Fast flow tested many years ago now. IIRC mine flow 280+ at .400, 335-ish at .500 and 360+ at .600

My 517 runs a Larry Smith ported '337 intake and a Bullet HR with 264/268 @.050 and around .600 lift with 1.6 rockers. The only difference is my motor's static is about 11.5:1 and I run the cam in early at 102 ICL with a 108 spread. It's a beast at all RPM and I run a fairly tight 4400 stall 9 1/2" converter with 3.54 gears in a 4000 lb w/d 70 charger. It revs like a comp eliminator motor. I think with a 10.5 motor I'd drop down to something like a 255/259 Ultradyne solid street roller Roller with the .4033 endurance lobes....which would match my present .200-up lift durations and still be mild enough for street driving. You can get a 1.7:1 hughes rocker to take the advertised lift from .605 to .680 ish, that would be the way I'd go for your combo.

That said if I were running an O/D for 70 mph with my motor for sum 70 mph cruising the cam is probably a little big unless you're cruising at maybe 2800. I can't imagine trying to hook up my motor with a stick shift unless I could get a really wide gear pattern, there's just too much torque and the motor is too responsive for street tires to deal with.

With the value of 2nd gen Chargers through the roof I only cruise the car and don't really race it for fear of buckling the quarter panel seams so I'm going to de-tune it a bit and probably either sell this motor or drop it into something like a 71 coronet that I can beat on properly.