I grew up in the '70's. We have much better heads, cams, etc., now. If you want to stay with the old parts, build the 283. If you want it to make more power, build something bigger.
'69 Camaro - 429 SBC Dart Iron Eagle 9.325" block, Crower crank, Crower 6" billet rods, Ross pistons (10:1), Total Seal rings, AFR 245 heads, T&D steel body shaft rockers, Cloyes Timing set, custom ground 4-7 swap solid roller 274/286 @ .050" with .704" lift, Dart single plane, Holley Dominator EFI on E85, Injector Dynamics ID2000 Injectors, Stef's #1705R oil pan, F2 Procharger, Lemons 2" primary 4" collector, ATI 9" blower converter