The 270 heads could be used if a person wanted a little more top end power and was willing to give up a little on the bottom end. I have a B-body project in my shop right now that has a 505 with TF270 heads and a 260/266 street roller cam. That engine made right at 700 hp with 650 torque peak at 4900. That guy went with 4.10 gears which are aa good match for the 270 heads, but a little steep for freeway driving. Personally I lean towards the 240 heads with 3.50 gears but if a person wants to go with the extra spicy then 270 heads and 4.10 gears will fill the bill.
I dont see any reason that the bigger ports would need that much more gear.
My 500" pump gas motor was setup extremely mild just for street cruising, it had Eddy heads that were ported to max wedge size, I ran 10.69 at 124mph driving it to and from the track with 3.23 gears. These big motors don't need 4.10 gears in my opinion.
Well as an example we drive to and from the track and race in full street trim (3800lbs@line) with a mild 589ci 10:1CR motor 440-2 intake MW heads, small solid roller and carb, 2.1/8th>2.1/4" step TTI's, 29" tyres and 4.10 Dana. We trap@6200-ish, max power on our motor runs from 5500>5900rpm then tails off slightly and we have run 10.35@130 best and 1.43 60's to date.
If we had 3.23's we'd trap@5000 with slip and have terrible 60's, it would be a total dog in my opinion even with our 700ftlbs+.
