I did a 273 in my 67 Barracuda fastback back in 91 or 92.030 over TRW pistons with 318 High swirl heads(#516 I think and came out about 10:1) 1.88/1.60 valves,510/286 Erson solid,reused the stock adjustable rockers with new Prods,Holley single plane, 625 AVS and cheap headrs.
I reused the finned VCs with wrinkle paint and the original air cleaner that I modded and painted the motor Chrysler red.
904 trans w/stock histall and 3.91 gears
The car made really good power to 7K.I never dynoed or made a pass with it but it was a lot of fun and revved really fast.
Pistons might be hard to find now though