273 or NOT 273?

That would be awesome. I'm wondering if I could use my 915 340 heads on the 273? (1.88 valves)
Yes it is doable. With a good set of 1.88 intake J heads Just clean up the bowls, port match the intake and heads, milled .040 and .038 on the intake side. Double check everything. You can run a smaller cam and still make that 67 fly. I ran a used 340 cam, 71 intake a TQ. My favorite engine of all time. Now, I'd run a custom solid cam, probably Racer Brown. But that was when you could buy good high octane gas for 10.5:1 compression. Not sure what tire would hold it with 4.56 gears... You should also run the Commando single exhaust, that would really blow their minds.