The SB Chevy 283 Block is standard 3.875" bore same size bore as a 307 L/J Block . The stock 283 uses the 3.000" Stroke crankshaft . By using the 3.250" Stroke Crankshaft and different pin height pistons Chevy made the 307 . How about your 283 bored 60+ over with 60 over 307 pistons and that 3.250" Crankshaft = 316ci Build . Not bad ? Or on some early 283's if they are check . They can be Punched out to a 4" bore and you could use standard 327 Pistons now you will have a S/J 327 Build .