I've built a 1.88 valve J head 273. Worked great, no proof, no time slips. 1972 340 J heads milled .040 and .038 in the intake side of the head, competition valve job, gasket matched on top and sides, cleaned up the bowls, chambers equalized to 64.8 cc. No bore notches, 10.5:1 TRW forged pistons, Speed Pro file to fit rings, bored and honed with torque plates, windage tray, HV 65 psi oil pump, Cloyes True roller timing chain, stock 340 cam, valve springs, shimmed rocker shafts, 71 340 intake and 4 speed TQ. Direct Connection electronic distributor and a chrome box. 340 flywheel and bellhousing, HP 440 10.95 scalloped clutch and pressure plate. 8 3/4 rear with choice of gears from 2.76 to 4.10. Shifted at 3,000 rpm minimum and 6,500 rpm regularly. All in a nondescript 1964 Barracuda. Most favorite car and engine ever!