I've run 28 spline for a long time in my Nova, but this is with a posi unit, spools are a lot harder on axles. I've got C-clip eliminators and would consider them manditory with a spool, just like the NHRA/IHRA track rules say - Any locked rear must have positive retention device on the axles.
Would need to know more about the torque converter and trans to pick a gear ratio, but if you are planning track time I am going to say you will be happier with the 4.10's. You can always try the 3.73's that are already in the rear with a spool or posi unit and see what they are like just to get an idea of which way you might want to go.
Your 327 will be happier with 4.56 gears if you don't have to hit the highway often, need to get it revv'ed up to get its power.
15 years ago I did a '76 nova for a girlfriend(her family was into racing too) with a 9-1 compression short rod 383, home ported 487x smogger heads, 2.02 valves, Crower 268/276° @ .050" .545"/.563" lift 108° seperation Solid cam installed 7 degrees advanced per Crowers instructions, Vic Jr and 750 Holley Vac Secondary, 1-5/8" headers, TH-350, 2800 stall, 4.11 gears. Went 12.50's with 12.10 potential, totally stock 28 spline 8.5" rear with factory Eaton posi from '75 Trans Am. Car was slow off the line(1.8xx 60" times) but had a good top end charge at 112 mph. 26" tall tire(McCreary/American Racer G-60/15 "dirt compound" IMCA tire makes a great DOT legal "cheater" tire). Car really needed 4.56 gears, or three more points compression LOL
There is a lot you can do to lighten the car in the bumper area - there are those heavy gas dampers that hold the bumper, and that heavy inner reinforcement beam inside the bumper shell on both ends of the car, almost 200 lbs in this excess stuff alone.