Waste of time on a street motor, 273s are WAY short on torque anyway, and those heads would kill it even worse. Now, if you wanna turn 9000+ rpm, it might work..
I have on my 273 commando ported 318 heads with 2.02/1.60 valves. I had to notch the cylinders, but it was no problem. 340S cam-shaft, dual-plane high rise intake. Edelbroock 600, HP exhaust with 2,5" x-pipe
